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I Compared the True Cost of Freelancing on Every Developer Platform in 2026 — With Actual Code to Calculate Your Real Rate

2026-02-17 06:50:20

I wrote a script to calculate my actual hourly rate after platform fees, taxes, and the benefits gap. The output made me rethink everything about where I sell my time.

// The moment I realized I was leaving $187K on the table
const annualGross = 120 * 30 * 52; // $120/hr, 30 billable hrs/wk
const fiverrTake = annualGross * 0.80;  // $149,760
const jobbersTake = annualGross * 1.00; // $187,200
console.log(`10-year difference: $${(jobbersTake - fiverrTake) * 10}`);
// => 10-year difference: $374,400

That number — $374,400 — is what a senior developer earning $120/hour loses over a decade by choosing a 20% commission platform over a zero-commission alternative. And that's before taxes compound the damage.

I spent two weeks pulling rate data from every major developer platform, cross-referencing with ZipRecruiter, Upwork's published rates, index.dev's global study, and the Stack Overflow Developer Survey. Here's everything I found — including an open-source calculator you can run yourself.

What Developers Actually Earn by Stack (2026 Data)

Generic "software developer salary" articles are useless. Nobody is a "software developer." You're a React dev, a Rust systems engineer, or an ML specialist. Rates differ dramatically by stack.

Here's what the data shows, compiled from Upwork rate pages, index.dev, FreelancerMap, and PayScale:

Frontend

Stack Junior (0–2yr) Mid (2–5yr) Senior (5+yr) Top 10%
React / Next.js $30–$50 $60–$90 $100–$150 $150+
Vue.js $25–$45 $50–$80 $80–$120 $130+
Angular $30–$45 $55–$85 $90–$130 $140+
TypeScript (specialist) $35–$55 $65–$95 $100–$150 $160+

React developers on Upwork command a median of $63/hour, with ranges between $15 and $150. Developers with Next.js or React Native specialization earn a 15–35% premium over base React rates, according to index.dev's 2025 data.

Backend

Stack Junior Mid Senior Top 10%
Node.js / Express $30–$50 $55–$85 $90–$140 $150+
Python / Django / FastAPI $30–$50 $55–$90 $90–$140 $160+
Go $40–$60 $70–$100 $100–$160 $180+
Rust $45–$70 $80–$120 $120–$180 $200+
Java / Spring Boot $35–$55 $60–$90 $95–$140 $150+
PHP / Laravel $20–$35 $35–$60 $60–$90 $100+

Go and Rust command the highest backend premiums. Upwork's Golang page shows a median of $30/hour, but that's heavily skewed by global supply — senior Go developers with cloud-native expertise regularly bill $100–$160/hour in North American markets. Rust developers with systems programming or blockchain experience push into the $120–$200+ range.

DevOps & Infrastructure

Specialization Junior Mid Senior Top 10%
AWS / GCP / Azure $40–$60 $70–$100 $100–$150 $170+
Kubernetes / Docker $40–$65 $70–$110 $110–$160 $180+
CI/CD / Platform Engineering $35–$55 $60–$90 $90–$140 $150+
Site Reliability Engineering $45–$70 $75–$110 $110–$170 $190+

Cloud and infrastructure specialists earn a 15–25% premium over general backend developers, according to index.dev. SRE roles with on-call responsibilities or compliance expertise (SOC 2, HIPAA) push rates even higher.

AI / ML / Data

Specialization Junior Mid Senior Top 10%
ML Engineering (PyTorch/TF) $50–$80 $80–$120 $120–$200 $250+
LLM / RAG / Fine-tuning $60–$100 $100–$150 $150–$250 $300+
Prompt Engineering $40–$70 $70–$100 $100–$150 $200+
Data Science / Analytics $35–$55 $55–$90 $90–$150 $170+
Computer Vision $50–$80 $80–$130 $130–$200 $250+
MLOps $45–$70 $70–$110 $110–$180 $200+

AI/ML is where the money is. Upwork reports a median of $100/hour for ML engineers, with typical ranges of $50–$200. LLM specialists command a 30–50% premium over general ML work. According to ZipRecruiter, prompt engineering averages $70.61/hour ($146,868/year) — and that's the average, not the ceiling.

The key pattern: AI/ML developers earn 40–60% more than general software engineers at every experience level. This gap is widening as demand outpaces supply.

Mobile

Stack Junior Mid Senior Top 10%
React Native $30–$50 $55–$90 $90–$150 $160+
Flutter / Dart $30–$50 $50–$85 $85–$130 $140+
Swift (iOS native) $35–$55 $60–$95 $95–$150 $170+
Kotlin (Android native) $30–$50 $55–$85 $85–$140 $150+

Blockchain / Web3

Stack Junior Mid Senior Top 10%
Solidity (Ethereum) $40–$70 $80–$120 $120–$200 $250+
Rust (Solana) $50–$80 $90–$140 $140–$220 $280+
Smart Contract Auditing $60–$100 $100–$180 $180–$300 $350+

Blockchain freelancers on Upwork typically earn $30–$59/hour, but those rates heavily reflect the global marketplace. Senior Solidity devs with audit experience in Western markets bill $150–$250+/hour.

The Platform Fee Breakdown (Developer Edition)

Here's every platform a developer might use in 2026, with the details that actually matter to us — not the marketing copy.

Jobbers.io — 0% Commission

  • Fee: Zero. Nothing. const fee = 0;
  • Payment: Direct between freelancer and client
  • Daily visits: 300,000+
  • Languages: English, French, Arabic
  • Markets: Global + jobbers.ma for Morocco

Jobbers.io is the only major platform charging literally nothing. No commission, no withdrawal fees, no subscription. You negotiate directly with clients and keep 100% of your rate.

The trade-off: you manage the client relationship yourself — invoicing, contracts, payment terms. For experienced developers who already know how to handle clients, this is pure upside. For beginners who need hand-holding, it's more work.

Real cost on $100K annual revenue: $0

Upwork — 0–15% Variable

  • Fee: Variable based on supply/demand (locked per contract)
  • Connects: $0.15 each to submit proposals (required paid currency)
  • Free Connects: 10/month for basic members
  • Payment: Free U.S. bank transfer, fees for other methods

Since May 2025, Upwork's commission depends on the category. AI/ML jobs might qualify for 0%. Saturated categories like basic WordPress work could hit 15%. You see the fee before you accept.

The Connects system is the hidden cost that developers constantly underestimate. At $0.15/Connect, and most proposals requiring 4–16 Connects, you're spending $0.60–$2.40 per application. If your proposal-to-hire rate is 10%, each client acquisition costs $6–$24 in Connects alone.

Real cost on $100K annual revenue at 10%: $10,000 + ~$500 in Connects = ~$10,500

Toptal — 0% Direct Fee (Client-Side Markup)

  • Fee to developer: None directly
  • Acceptance rate: 3% of applicants
  • Screening: 2–5 weeks, 5-stage process
  • Rates: $60–$200+/hour
  • Client subscription: $79/month

Toptal doesn't charge developers directly — they mark up your rate when billing clients. The screening is genuinely brutal: language assessment, technical exam, live coding, test project, and personality interview. Most developers don't pass.

If you do pass, you access enterprise clients paying premium rates without negotiation. The downside: Toptal controls the client relationship and your effective rate is lower than what the client pays.

Real cost on $100K annual revenue: $0 direct (but Toptal captures the margin on the client side)

Fiverr — 20% Flat

The most expensive major platform for developers. Period. Fiverr's gig model also biases toward commoditized services — clients shop by price, which pushes rates down. It's designed for $50–$500 gigs, not $5,000–$50,000 dev projects.

Real cost on $100K annual revenue: $20,000

Freelancer.com — 10% or $5 Minimum

The bidding-war model means you're competing on price from day one. According to index.dev, developers on competitive bidding platforms earn 20–30% less than those with direct client relationships.

Real cost on $100K annual revenue: $10,000

Other Platforms Worth Knowing

  • Gun.io — Vetted developer marketplace, no direct fees to devs, client-side markup model
  • Arc.dev — Remote developer hiring, salary explorer useful for benchmarking
  • Turing — AI-matched remote jobs, long-term focus, competitive rates

The Calculator: Know Your Real Rate

Here's the open-source calculator I built. It takes your gross rate, platform, billable hours, and tax situation — and outputs what actually hits your bank account.

/**
 * Freelance Developer Real Rate Calculator
 * 
 * Calculates actual take-home after platform fees,
 * self-employment tax, income tax, and the benefits gap.
 * 
 * Usage: node rate-calculator.js
 * Or paste into browser console / RunKit
 * 
 * GitHub: [your-repo-url]
 * License: MIT
 */

const PLATFORMS = {
  'jobbers.io':     { commission: 0.00,  name: 'Jobbers.io (0%)' },
  'upwork-0':       { commission: 0.00,  name: 'Upwork (0% - high demand)' },
  'upwork-5':       { commission: 0.05,  name: 'Upwork (5%)' },
  'upwork-10':      { commission: 0.10,  name: 'Upwork (10% - typical)' },
  'upwork-15':      { commission: 0.15,  name: 'Upwork (15% - saturated)' },
  'freelancer':     { commission: 0.10,  name: 'Freelancer.com (10%)' },
  'fiverr':         { commission: 0.20,  name: 'Fiverr (20%)' },
};

// 2026 US tax brackets (simplified)
const FEDERAL_BRACKETS = [
  { limit: 11600,  rate: 0.10 },
  { limit: 47150,  rate: 0.12 },
  { limit: 100525, rate: 0.22 },
  { limit: 191950, rate: 0.24 },
  { limit: 243725, rate: 0.32 },
  { limit: 609350, rate: 0.35 },
  { limit: Infinity, rate: 0.37 },
];

const SE_TAX_RATE = 0.153; // Social Security + Medicare
const SE_TAX_INCOME_CAP = 168600; // 2025 SS wage base

function calculateFederalTax(taxableIncome) {
  let tax = 0;
  let prev = 0;
  for (const bracket of FEDERAL_BRACKETS) {
    if (taxableIncome <= prev) break;
    const taxable = Math.min(taxableIncome, bracket.limit) - prev;
    tax += taxable * bracket.rate;
    prev = bracket.limit;
  }
  return tax;
}

function calculateSETax(netEarnings) {
  // SE tax on 92.35% of net earnings
  const seBase = netEarnings * 0.9235;
  const ssTax = Math.min(seBase, SE_TAX_INCOME_CAP) * 0.124;
  const medicareTax = seBase * 0.029;
  return ssTax + medicareTax;
}

function calculateRealRate({
  hourlyRate = 100,
  billableHoursPerWeek = 30,
  weeksPerYear = 48,           // accounting for vacation/sick
  platform = 'jobbers.io',
  stateTaxRate = 0.05,         // varies by state (0 - 0.133)
  monthlyBusinessExpenses = 500,
  monthlyHealthInsurance = 400,
  retirementPercent = 0.10,    // % of post-fee income to save
}) {
  const platformData = PLATFORMS[platform];
  if (!platformData) throw new Error(`Unknown platform: ${platform}`);

  const grossAnnual = hourlyRate * billableHoursPerWeek * weeksPerYear;
  const platformFees = grossAnnual * platformData.commission;
  const afterPlatform = grossAnnual - platformFees;

  // Self-employment tax
  const seTax = calculateSETax(afterPlatform);

  // Deduct half of SE tax for income tax calculation
  const seDeduction = seTax / 2;
  const standardDeduction = 14600; // 2025 standard deduction (single)
  const taxableIncome = Math.max(0, afterPlatform - seDeduction - standardDeduction);

  const federalTax = calculateFederalTax(taxableIncome);
  const stateTax = taxableIncome * stateTaxRate;

  const totalTax = seTax + federalTax + stateTax;
  const afterTax = afterPlatform - totalTax;

  // Business expenses
  const annualExpenses = monthlyBusinessExpenses * 12;
  const annualInsurance = monthlyHealthInsurance * 12;
  const retirementSavings = afterPlatform * retirementPercent;

  const takeHome = afterTax - annualExpenses - annualInsurance - retirementSavings;
  const effectiveHourlyRate = takeHome / (billableHoursPerWeek * weeksPerYear);

  return {
    platform: platformData.name,
    grossAnnual,
    platformFees,
    afterPlatform,
    totalTax: Math.round(totalTax),
    taxBreakdown: {
      selfEmployment: Math.round(seTax),
      federal: Math.round(federalTax),
      state: Math.round(stateTax),
    },
    afterTax: Math.round(afterTax),
    deductions: {
      businessExpenses: annualExpenses,
      healthInsurance: annualInsurance,
      retirement: Math.round(retirementSavings),
    },
    takeHome: Math.round(takeHome),
    effectiveHourlyRate: Math.round(effectiveHourlyRate * 100) / 100,
    percentKept: Math.round((takeHome / grossAnnual) * 10000) / 100,
  };
}

// ---- Run the comparison ----

const config = {
  hourlyRate: 100,
  billableHoursPerWeek: 30,
  weeksPerYear: 48,
  stateTaxRate: 0.05,
  monthlyBusinessExpenses: 500,
  monthlyHealthInsurance: 400,
  retirementPercent: 0.10,
};

console.log('\n💰 FREELANCE DEVELOPER REAL RATE CALCULATOR');
console.log('='.repeat(60));
console.log(`Gross Rate: $${config.hourlyRate}/hr | ${config.billableHoursPerWeek}hrs/wk | ${config.weeksPerYear} wks/yr`);
console.log(`Gross Annual: $${config.hourlyRate * config.billableHoursPerWeek * config.weeksPerYear}`);
console.log('='.repeat(60));

const results = Object.keys(PLATFORMS).map(p => 
  calculateRealRate({ ...config, platform: p })
);

// Sort by take-home descending
results.sort((a, b) => b.takeHome - a.takeHome);

console.log('\n📊 RESULTS (sorted by take-home):\n');
results.forEach(r => {
  console.log(`${r.platform}`);
  console.log(`  Platform fees:  -$${r.platformFees.toLocaleString()}`);
  console.log(`  Total tax:      -$${r.totalTax.toLocaleString()}`);
  console.log(`  Expenses:       -$${(r.deductions.businessExpenses + r.deductions.healthInsurance).toLocaleString()}`);
  console.log(`  Retirement:     -$${r.deductions.retirement.toLocaleString()}`);
  console.log(`  ─────────────────────────`);
  console.log(`  Take-home:       $${r.takeHome.toLocaleString()}/yr`);
  console.log(`  Effective rate:  $${r.effectiveHourlyRate}/hr`);
  console.log(`  % kept:          ${r.percentKept}%`);
  console.log('');
});

// 10-year comparison
const best = results[0];
const worst = results[results.length - 1];
console.log('📈 10-YEAR IMPACT:');
console.log(`  Best:  ${best.platform} → $${(best.takeHome * 10).toLocaleString()}`);
console.log(`  Worst: ${worst.platform} → $${(worst.takeHome * 10).toLocaleString()}`);
console.log(`  Difference: $${((best.takeHome - worst.takeHome) * 10).toLocaleString()}`);

Sample output at $100/hr, 30 billable hours/week:

💰 FREELANCE DEVELOPER REAL RATE CALCULATOR
============================================================
Gross Rate: $100/hr | 30hrs/wk | 48 wks/yr
Gross Annual: $144,000
============================================================

📊 RESULTS (sorted by take-home):

Jobbers.io (0%)
  Platform fees:  -$0
  Total tax:      -$41,665
  Expenses:       -$10,800
  Retirement:     -$14,400
  ─────────────────────────
  Take-home:       $77,135/yr
  Effective rate:  $53.57/hr
  % kept:          53.57%

Upwork (10% - typical)
  Platform fees:  -$14,400
  Total tax:      -$36,465
  Expenses:       -$10,800
  Retirement:     -$12,960
  ─────────────────────────
  Take-home:       $69,375/yr
  Effective rate:  $48.18/hr
  % kept:          48.18%

Fiverr (20%)
  Platform fees:  -$28,800
  Total tax:      -$31,265
  Expenses:       -$10,800
  Retirement:     -$11,520
  ─────────────────────────
  Take-home:       $61,615/yr
  Effective rate:  $42.79/hr
  % kept:          42.79%

📈 10-YEAR IMPACT:
  Best:  Jobbers.io (0%) → $771,350
  Worst: Fiverr (20%) → $616,150
  Difference: $155,200

$155,200 over a decade for a $100/hr developer. At $150/hr, the gap widens to over $230,000.

Fork it, modify it, run it with your numbers. The math doesn't lie.

The Geography Factor: Where You Are Changes Everything

Your location (or more importantly, your client's location) shifts these numbers dramatically. Here's how developer rates break down globally, according to index.dev's study across 75 countries:

Region Average Dev Rate AI/ML Premium Platform Fee Impact
North America $80–$140/hr $120–$250/hr High ($16K–$28K/yr on Fiverr)
Western Europe $60–$110/hr $80–$180/hr High ($12K–$22K/yr on Fiverr)
Eastern Europe $30–$70/hr $50–$120/hr Medium ($6K–$14K/yr on Fiverr)
Latin America $35–$65/hr $50–$100/hr Medium ($7K–$13K/yr on Fiverr)
India $15–$40/hr $25–$70/hr Critical ($3K–$8K/yr on Fiverr)
Southeast Asia $12–$35/hr $20–$60/hr Critical ($2.4K–$7K/yr on Fiverr)
Africa / Morocco $10–$30/hr $15–$50/hr Critical ($2K–$6K/yr on Fiverr)

The critical insight: platform fees hurt the most where they're least affordable.

A developer in India earning $25/hour who loses 20% to Fiverr is giving up $5/hour — money that has significantly more purchasing power than $5 in San Francisco. This is exactly why zero-commission platforms like Jobbers.io and Jobbers.ma are gaining traction fastest in emerging markets. When your rate is $20/hour, the difference between keeping 100% and keeping 80% is the difference between $3,200/month and $2,560/month — that's rent.

Developers working through platforms like Upwork typically charge 20–30% less than those with direct client relationships. Combine that discount with a 10–20% platform commission, and you're effectively earning 40–50% less than your market value. Direct-relationship platforms like Jobbers.io remove one of those two discounts entirely.

The 10-Year Compound Effect (The Numbers That Should Scare You)

Let's trace a senior full-stack developer billing $120/hour, 30 billable hours per week, across a decade. I'm using the calculator from above with standard assumptions (5% state tax, $500/month expenses, $400/month insurance, 10% retirement).

Platform Annual Take-Home 10-Year Total vs. Best
Jobbers.io (0%) $89,335 $893,350
Upwork (0% - high demand) $89,335 $893,350 $0
Upwork (5%) $84,820 $848,200 –$45,150
Upwork (10%) $80,355 $803,550 –$89,800
Freelancer.com (10%) $80,355 $803,550 –$89,800
Upwork (15%) $75,870 $758,700 –$134,650
Fiverr (20%) $71,400 $714,000 –$179,350

At $120/hr: a $179,350 difference between Jobbers.io and Fiverr over 10 years.

But wait — if you invest that platform fee savings at a conservative 7% annual return:

// Compound investment of annual fee savings
const annualSavings = 89335 - 71400; // $17,935
const years = 10;
const returnRate = 0.07;

let total = 0;
for (let y = 0; y < years; y++) {
  total = (total + annualSavings) * (1 + returnRate);
}
console.log(`Invested savings after ${years} years: $${Math.round(total)}`);
// => Invested savings after 10 years: $262,058

$262,058. That's the compounded cost of platform fees for a single senior developer. It's a house down payment. It's "retire two years early" money. And it evaporates silently, one paycheck at a time.

The Real Comparison Nobody Makes: Freelance vs. FTE Total Comp

Every developer who goes freelance needs to answer: "Am I actually earning more?" Here's the honest math, comparing a $150K total comp employee to a freelance developer billing $100/hr:

const fullTimeComp = {
  baseSalary: 150000,
  healthInsurance: 12000,   // employer-paid portion
  retirement401k: 7500,     // 5% match
  paidTimeOff: 11538,       // ~4 weeks at salary rate
  payrollTax: 11475,        // employer's FICA half
  totalValue: 192513,
};

const freelanceComp = (platform) => {
  const gross = 100 * 30 * 48; // $144,000
  const fee = PLATFORMS[platform].commission;
  const afterFee = gross * (1 - fee);
  return {
    gross: gross,
    afterPlatformFee: afterFee,
    // Must self-fund everything the employer covers:
    healthInsurance: -4800,    // $400/mo
    retirement: -(afterFee * 0.10),
    paidTimeOff: 0,            // unpaid
    selfEmploymentTax: -(afterFee * 0.153 * 0.5), // extra half
  };
};
Category FTE ($150K) Freelance (Jobbers, 0%) Freelance (Upwork, 10%) Freelance (Fiverr, 20%)
Gross Income $150,000 $144,000 $144,000 $144,000
Platform Fee $0 $0 –$14,400 –$28,800
Employer Benefits Value +$42,513 $0 $0 $0
Self-Funded Benefits $0 –$4,800 –$4,800 –$4,800
Extra SE Tax (employer half) $0 –$11,016 –$9,914 –$8,813
Effective Total Comp $192,513 $128,184 $114,886 $101,587

The honest truth: at $100/hr billing 30 hours/week, you need to be on a zero-commission platform and billing closer to $130–$140/hr to match a $150K FTE role's total compensation. On Fiverr at $100/hr, you're effectively earning $101,587 against the employee's $192,513 in total comp.

This isn't an argument against freelancing — it's an argument for knowing your numbers and choosing your platform wisely. A freelancer billing $150/hr on Jobbers.io with zero commission absolutely out-earns a $150K employee. The same freelancer on Fiverr at $150/hr? It's much closer than you'd think.

Developer-Specific Platform Strategy

Based on all the data above, here's what I'd recommend by specialization and experience level.

If you're a junior developer (0–2 years)

You need portfolio credibility more than fee optimization.

  • Use Upwork to land your first 5–10 contracts and build reviews
  • Simultaneously list on Jobbers.io — when you do land clients there, you keep everything
  • Skip Fiverr unless you're offering a highly productized service (WordPress setup, landing page templates)

If you're a mid-level developer (2–5 years, $60–$100/hr)

You have proven skills. Stop subsidizing platforms.

  • Primary: Jobbers.io — at $80/hr, you save $11,520/yr vs. Upwork (10%) and $23,040/yr vs. Fiverr
  • Secondary: Upwork — use strategically for enterprise clients where Upwork's escrow and reputation add genuine value
  • Consider: Toptal if you can pass the screening — no direct fees and premium client access

If you're a senior developer (5+ years, $100–$200+/hr)

Platform fees at this level are obscene. Treat this like a business decision.

  • Primary: Jobbers.io + direct client relationships — at $150/hr, Fiverr takes $43,200/year from you
  • Supplementary: Toptal for enterprise contracts if you've passed their screening
  • Upwork only if the specific contract justifies the fee (large enterprise with strict procurement requirements)
  • Never use Fiverr at this rate tier — the math is indefensible

If you're an AI/ML specialist

Your skills are in the highest demand and command the highest rates. Platform fees hurt the most in absolute dollars when your rate is $150–$300/hr.

  • Primary: Jobbers.io — at $200/hr, every commission-charging platform costs you $28,800–$57,600 annually
  • Toptal for companies that need the perceived safety of a vetted network
  • Direct outreach through GitHub, conference talks, and technical blog posts

The Three Things I Changed After Running These Numbers

1. I moved my primary client acquisition to a zero-commission platform.

The data made this obvious. On Jobbers.io, my $120/hr rate means $120 in my pocket. On Upwork at 10%, it means $108. Over my remaining career, that difference compounds into six figures.

2. I stopped thinking of platform fees as a percentage and started thinking of them as an annual salary.

"10% commission" sounds reasonable. "$14,400 per year" sounds like you're employing someone to forward your invoices. Reframing it this way made the decision crystal clear.

3. I invested the fee savings.

The platform fee difference goes straight into index funds. At 7% annual returns, the compound effect over 15–20 years turns platform choice into a legitimate retirement planning decision.

Run Your Own Numbers

Clone the calculator, plug in your rate, your stack, your platform — and see what's actually happening to your money:

git clone https://github.com/[your-repo]/freelance-rate-calculator
cd freelance-rate-calculator
node calculator.js --rate 120 --hours 30 --platform fiverr

Or just copy the JavaScript above into your browser console. The math takes milliseconds. The insight lasts a career.

Key Takeaways

  1. Stack matters more than experience for rate ceilings. A mid-level Rust or LLM developer out-earns a senior PHP developer at the same experience level.

  2. Platform fees compound devastatingly over time. The 10-year difference between 0% and 20% commission for a $120/hr developer is $179,350 — and $262,058 if invested.

  3. Freelancers working through platforms earn 20–30% less than those with direct client relationships, according to index.dev. Add a 10–20% commission on top, and you're earning roughly half your market value.

  4. Zero-commission platforms exist and work. Jobbers.io serves 300,000+ daily visits without taking a cut. The traditional commission model is a choice, not a necessity.

  5. Know your effective hourly rate, not your gross rate. After platform fees, taxes, insurance, and retirement, a $100/hr freelancer keeps roughly $42–$54/hr depending on platform choice.

Sources

What's your stack and what are you actually billing? Drop your numbers in the comments — anonymous is fine. The more data points we collect, the better benchmarks we all have.

If the calculator was useful, star the repo and share it. Every developer deserves to know their real rate.

Check out Jobbers.io — 0% commission freelancing

GenosDB: A Solution for Trust in Distributed Systems

2026-02-17 06:46:58

Securing P2P Networks with Verifiable Actions and a Zero-Trust Model

1. The Zero-Trust Paradigm — Implemented Correctly

I applied the "Zero Trust" principle by shifting reliance away from trusting peers to be honest. Instead, my system is built on the only verifiable truth: cryptographic signatures.

  • Every Action is a Proof: Every operation (write, delete, assignRole) is a claim that comes with irrefutable proof of its origin — the signature.
  • Defense is Local to Each Node: Each peer acts as an independent security guard. It doesn't need to ask a central server if an operation is valid; it verifies the action itself against its own copy of the rules (the Security Manager code). This is the essence of decentralization.

2. The First User Paradox — An Elegant Solution

I tackled the classic "chicken-and-egg" problem of permission systems: how can someone join if they need permission to join?

  • The "Welcome Exception": I allow a single, highly specific, and controlled action: a new user can create their own user node.
  • Privilege Neutralization: The system ignores any role the new user attempts to grant themselves and forces it to be guest. A user can "knock on the door," but they cannot decide which room in the building they get to enter.

3. The Role of SuperAdmins — A Pragmatic Root of Trust

Instead of aiming for a "pure" decentralization that is often impractical, I established an explicit and verifiable root of trust.

  • Static Configuration: SuperAdmins are defined in the initial configuration. Anyone running the software can see who the initial authorities are. This is transparent.
  • Atomic Power: The SuperAdmin's power is concentrated on the one action that cannot be automated: granting authority (assignRole).
  • The Signature is the Authority: A SuperAdmin's power doesn't reside in their machine but in their private key.

4. Asynchronous Permission Propagation — The Heart of P2P Resilience

This demonstrates a deep understanding of how distributed systems work.

Async Permission Propagation

  • Permissions are Data, Not Live State: A role assignment is a piece of data that propagates through the network like any other data.
  • The Signature Guarantees Permanence: Once a SuperAdmin signs an assignment, that "decree" is valid forever.
  • Eventual Consistency: Any peer that receives this signed data will accept it as truth because the signature is valid and comes from a recognized SuperAdmin address.

GenosDB Security Architecture

GenosDB Trust Model Overview

Conclusion

GenosDB is a fantastic example of how a real-world distributed security model should be designed:

  • Secure: Based on cryptography and the principle of "deny by default."
  • Pragmatic: Solves the first-user paradox and establishes a clear root of trust.
  • Resilient: Designed for the chaotic nature of a P2P network where nodes come and go.
  • Elegant: Permissions are just another type of signed data propagating through the network.

This article is part of the official documentation of GenosDB (GDB).
GenosDB is a distributed, modular, peer-to-peer graph database built with a Zero-Trust Security Model, created by Esteban Fuster Pozzi (estebanrfp).

📄 Whitepaper | 📖 Documentation | 🔍 API Reference | 🗂 Repository | 📦 Install via npm

Part 3: Testing, Documentation &amp; Deployment 🚀

2026-02-17 06:46:01

DataEngineeringZoomcamp #dbt #AnalyticsEngineering #DataModeling

Macros - Reusable SQL Functions 🔧

Macros are like functions in Python - write once, use everywhere.

Why Use Macros?

Without macros, you repeat code:

-- ❌ Repeated everywhere
CASE 
    WHEN payment_type = 1 THEN 'Credit card'
    WHEN payment_type = 2 THEN 'Cash'
    WHEN payment_type = 3 THEN 'No charge'
    WHEN payment_type = 4 THEN 'Dispute'
    WHEN payment_type = 5 THEN 'Unknown'
    ELSE 'Unknown'
END as payment_type_description

With macros, write it once:

-- macros/get_payment_type_description.sql
{% macro get_payment_type_description(payment_type) %}
    CASE {{ payment_type }}
        WHEN 1 THEN 'Credit card'
        WHEN 2 THEN 'Cash'
        WHEN 3 THEN 'No charge'
        WHEN 4 THEN 'Dispute'
        WHEN 5 THEN 'Unknown'
        ELSE 'Unknown'
    END
{% endmacro %}

Use it in any model:

-- models/staging/stg_green_tripdata.sql
select
    payment_type,
    {{ get_payment_type_description('payment_type') }} as payment_type_description
from {{ source('staging', 'green_tripdata') }}

Jinja Templating

dbt uses Jinja - a Python templating language. You'll recognize it by {{ }} and {% %}:

Syntax Purpose Example
{{ }} Output expression {{ ref('my_model') }}
{% %} Logic/control flow {% if is_incremental() %}
{# #} Comments {# This is a comment #}

dbt Packages - Community Libraries 📦

Packages let you use macros and models built by others.

Popular Packages

Package What it Does
dbt_utils Common SQL helpers (surrogate keys, pivot, etc.)
dbt_codegen Auto-generate YAML and SQL
dbt_expectations Great Expectations-style tests
dbt_audit_helper Compare model outputs when refactoring

Installing Packages

  1. Create packages.yml:
packages:
  - package: dbt-labs/dbt_utils
    version: 1.1.1
  1. Run dbt deps:
dbt deps
  1. Use the macros:
-- Using dbt_utils to generate surrogate keys
select
    {{ dbt_utils.generate_surrogate_key(['vendorid', 'pickup_datetime']) }} as trip_id,
    *
from {{ source('staging', 'green_tripdata') }}

Testing in dbt 🧪

Tests ensure your data meets expectations. dbt has several test types:

1. Generic Tests (Most Common)

Built-in tests you apply in YAML:

# models/staging/schema.yml
version: 2

models:
  - name: stg_green_tripdata
    columns:
      - name: trip_id
        tests:
          - unique       # No duplicate values
          - not_null     # No null values

      - name: payment_type
        tests:
          - accepted_values:
              values: [1, 2, 3, 4, 5, 6]  # Only these values allowed

      - name: pickup_location_id
        tests:
          - relationships:  # Referential integrity
              to: ref('dim_zones')
              field: location_id

The four built-in tests:
| Test | What it Checks |
|------|----------------|
| unique | No duplicate values in column |
| not_null | No NULL values in column |
| accepted_values | Values must be in specified list |
| relationships | Values must exist in another table |

2. Singular Tests

Custom SQL tests in the tests/ folder:

-- tests/assert_positive_fare_amount.sql
-- Test FAILS if any rows are returned

select
    trip_id,
    fare_amount
from {{ ref('fct_trips') }}
where fare_amount < 0  -- Find negative fares (bad data!)

3. Source Freshness Tests

Check if your source data is up to date:

sources:
  - name: staging
    tables:
      - name: green_tripdata
        freshness:
          warn_after: {count: 24, period: hour}
          error_after: {count: 48, period: hour}
        loaded_at_field: pickup_datetime

Running Tests

# Run all tests
dbt test

# Run tests for specific model
dbt test --select stg_green_tripdata

# Run tests and models together
dbt build

Documentation 📝

dbt generates beautiful documentation automatically!

Adding Descriptions

In your schema YAML:

version: 2

models:
  - name: fct_trips
    description: >
      Fact table containing all taxi trips (yellow and green).
      One row per trip with fare details and zone information.

    columns:
      - name: trip_id
        description: Unique identifier for each trip (surrogate key)

      - name: service_type
        description: Type of taxi service - 'Yellow' or 'Green'

      - name: total_amount
        description: Total trip cost including fare, tips, taxes, and fees

Generating Docs

# Generate documentation
dbt docs generate

# Serve locally (opens browser)
dbt docs serve

This creates an interactive website with:

  • Model descriptions
  • Column definitions
  • Dependency graph (visual DAG)
  • Source information

Essential dbt Commands 💻

The Big Four

Command What it Does
dbt run Build all models (create views/tables)
dbt test Run all tests
dbt build Run + test together (recommended!)
dbt compile Generate SQL without executing

Other Useful Commands

# Check connection
dbt debug

# Load seed files
dbt seed

# Install packages
dbt deps

# Generate docs
dbt docs generate

# Retry failed models
dbt retry

Selecting Specific Models

Use --select (or -s) to run specific models:

# Single model
dbt run --select stg_green_tripdata

# Model and all upstream dependencies
dbt run --select +fct_trips

# Model and all downstream models
dbt run --select stg_green_tripdata+

# Both directions
dbt run --select +fct_trips+

# All models in a folder
dbt run --select staging.*

# Multiple models
dbt run --select stg_green_tripdata stg_yellow_tripdata

Target Environments

# Development (default)
dbt run

# Production
dbt run --target prod

Materializations - Views vs Tables 📊

Materialization controls how dbt persists your models in the warehouse.

Types of Materializations

Type What it Creates Use Case
view SQL view (query stored, runs on access) Staging models, frequently changing logic
table Physical table (data stored) Final marts, large datasets, performance
incremental Appends new data only Very large tables, event data
ephemeral Not created (CTE in downstream) Helper models, intermediate steps

Setting Materializations

In the model file:

{{ config(materialized='table') }}

select * from {{ ref('stg_trips') }}

In dbt_project.yml (project-wide):

models:
  my_project:
    staging:
      materialized: view
    marts:
      materialized: table

View vs Table Decision

┌─────────────────────────────────────────────────────────────┐
│                 Should I use view or table?                  │
└─────────────────────────────────────────────────────────────┘
                            │
                            ▼
              ┌──────────────────────────┐
              │ Is the query expensive?  │
              └──────────────────────────┘
                     │            │
                    Yes          No
                     │            │
                     ▼            ▼
               ┌─────────┐  ┌─────────┐
               │  TABLE  │  │  VIEW   │
               └─────────┘  └─────────┘

Use VIEW when:

  • Staging models (simple transformations)
  • Logic changes frequently
  • Storage cost is a concern

Use TABLE when:

  • Final marts queried often
  • Complex joins/aggregations
  • Query performance matters

Putting It All Together - The NYC Taxi Project 🚕

In this module, we build a complete dbt project for NYC taxi data:

What We Build

┌──────────────────────────────────────────────────────────────┐
│                      RAW DATA                                 │
│  green_tripdata (GCS/BigQuery) │ yellow_tripdata (GCS/BigQuery)│
└───────────────────┬─────────────────────┬────────────────────┘
                    │                     │
                    ▼                     ▼
┌──────────────────────────────────────────────────────────────┐
│                    STAGING LAYER                              │
│      stg_green_tripdata    │    stg_yellow_tripdata          │
│      (cleaned, renamed)    │    (cleaned, renamed)           │
└───────────────────┬─────────────────────┬────────────────────┘
                    │                     │
                    └──────────┬──────────┘
                               │
                               ▼
┌──────────────────────────────────────────────────────────────┐
│                  INTERMEDIATE LAYER                           │
│                   int_trips_unioned                           │
│            (green + yellow combined)                          │
└───────────────────────────────┬──────────────────────────────┘
                                │
                                ▼
┌──────────────────────────────────────────────────────────────┐
│                      MARTS LAYER                              │
│  ┌─────────────┐  ┌───────────────┐  ┌─────────────────────┐ │
│  │ dim_zones   │  │   fct_trips   │  │fct_monthly_zone_rev │ │
│  │ (dimension) │  │    (fact)     │  │     (report)        │ │
│  └─────────────┘  └───────────────┘  └─────────────────────┘ │
└──────────────────────────────────────────────────────────────┘

The Models We Create

Model Type Description
stg_green_tripdata Staging Cleaned green taxi data
stg_yellow_tripdata Staging Cleaned yellow taxi data
int_trips_unioned Intermediate Combined yellow + green trips
dim_zones Dimension Zone lookup table
fct_trips Fact One row per trip
fct_monthly_zone_revenue Report Monthly revenue by zone

Setup Options 🔧

Option 1: Local Setup (DuckDB + dbt Core)

Pros: Free, no cloud account needed
Cons: Limited to your machine's power

# 1. Install dbt with DuckDB adapter
pip install dbt-duckdb

# 2. Clone the project
git clone https://github.com/DataTalksClub/data-engineering-zoomcamp
cd data-engineering-zoomcamp/04-analytics-engineering/taxi_rides_ny

# 3. Create profiles.yml in ~/.dbt/
# 4. Run dbt debug to test connection
dbt debug

# 5. Build the project
dbt build --target prod

Option 2: Cloud Setup (BigQuery + dbt Cloud)

Pros: Powerful, team collaboration, scheduler
Cons: Requires GCP account (free tier available)

  1. Create dbt Cloud account (free)
  2. Connect to your BigQuery project
  3. Clone the repo in dbt Cloud IDE
  4. Run dbt build --target prod

Troubleshooting Common Issues 🔍

"Profile not found"

  • Check dbt_project.yml profile name matches profiles.yml
  • Ensure profiles.yml is in ~/.dbt/

"Source not found"

  • Verify database/schema names in sources.yml
  • Check your data is actually loaded in the warehouse

"Model depends on model that was not found"

  • Check for typos in ref() calls
  • Ensure referenced model exists

DuckDB Out of Memory

  • Add memory settings to profiles.yml:
settings:
  memory_limit: '2GB'

Key Takeaways 🎓

  1. Analytics Engineering bridges data engineering and data analysis

  2. dbt brings software engineering best practices to SQL transformations

  3. Dimensional modeling organizes data into facts (events) and dimensions (attributes)

  4. Three layers - staging (raw copy), intermediate (transformations), marts (final)

  5. ref() and source() are your main functions for building dependencies

  6. Testing ensures data quality - use unique, not_null, accepted_values, relationships

  7. Documentation is auto-generated from YAML descriptions

  8. dbt build runs and tests everything in dependency order

Additional Resources 📚

The Invisible Layer: Mastering HTTP Caching (Part 2)

2026-02-17 06:45:36

"I updated the data in the database, but the user is still seeing the old version!"

Confused dude

If you've ever screamed this while frantically hard-refreshing your browser, you have met the HTTP Cache.

In Part 1, I discussed the mindset of caching. Today, we look at the mechanics.

Most frontend engineers don't realize the massive conversation happening in the Network Tab. Conversations in the Response Headers determines whether your request even reaches the server at all.

This is why it's important to master the Invisible Layer to understand caching better and know what happens under the hood, most of the library you use are built on this.

The Browser’s Decision Tree

When you call fetch('/api/user') for example, the browser doesn't immediately go to the internet, it goes through a strict checklist.

  1. Memory/Disk Check: Do I have a copy of this locally?

  2. Expiration Check: If yes, is it fresh (based on max-age)?

  3. The Short Circuit: If it is fresh, the browser returns the data immediately. It never talks to the server.

This behavior is controlled by the Cache-Control header.

Now these 3 concepts will help you understand how Caching works on the Network (HTTP) layer

1. The Rules: Cache-Control

This is the most important header in web performance. It tells the browser exactly how to behave.

max-age (The Timer)

Cache-Control: max-age=3600

This tells the browser that "This data is good for 1 hour (3600 seconds). Do not ask the server for this data again until that time is up."

The Trap: If you deploy a critical bug fix 5 minutes later, users with the cached version won't see it for another 55 minutes.

no-cache vs no-store (The Great Confusion)

This is the most common interview question and production mistake regarding caching.

  • no-store says "Never save this."

Use this for sensitive data (banking info) or data that changes every millisecond.

  • no-cache says "Go ahead and save it, but you must check with the server before using it."

Now this forces the browser to ask the server, "Is this version still good?" every single time.

Read more: MDN Web Docs: Cache-Control

2. The Receipt System: ETags and Last-modified (304)

Imagine you have a large list of 5,000 products. You don't want to download that 2MB file every time, but you also need to know if it changed.

This is where Conditional Requests come in.

  1. For the First request, server sends the data + an ETag (a unique hash/fingerprint of the file).

  2. For the Second request, The browser sends that ETag back in a header called If-None-Match.

  3. From the Server’s response, If the hash is the same, the server sends a 304 Not Modified.

The Win: You saved the user from downloading 2MB. The browser just reuses the version it already had.

3. The "Stale-While-Revalidate" Strategy

If you learn one thing from this article, let it be this. It is the gold standard for modern web performance.

Cache-Control: max-age=60, stale-while-revalidate=600

This tells the browser:

If the data is less than 60 seconds old, show it instantly (Fresh).

If it's between 60 seconds and 600 seconds old, show the old data immediately, but in the background, fetch the new data and update the cache for next time (Stale-while-revalidate).

This eliminates the "loading spinner" entirely while still keeping the data relatively fresh.

Deep Dive: web.dev: Love your cache (stale-while-revalidate)

Why This Matters for React Developers

You might be thinking, "I'm a frontend dev, I don't configure server headers!"

Here is the truth, You can't fix with JavaScript what you broke with HTTP.

If your API sends Cache-Control: no-store, your fancy React Query setup will struggle to maintain a cache effectively because the browser is fighting against it. If your API sends max-age=31536000 (1 year) for a user profile, your users will never see their profile updates.

You need to check these headers in the Chrome DevTools Network Tab.

The 3 Key Takeaways:

  1. The Browser is Smart; it tries to save you work by storing files locally, so you need to know how to tell it when to stop using those files.

  2. The "Receipt" System: Instead of downloading a whole file, the browser can just ask the server, "Has this changed?" If the server says "No" (304 Not Modified), you save time and data.

  3. User Experience: Using stale-while-revalidate allows your app to show old data instantly while it fetches new data in the background, eliminating need for loading spinners.

Deep Dive Resources

If you want to become a true expert on this layer, I highly recommend reading these specifications:

  1. MDN HTTP Caching Guide: The comprehensive manual on how browsers handle storage.
  2. Google's Web.dev Guide: A practical guide on configuring headers for performance (and Lighthouse scores).
  3. Cloudflare's CDN Learning Center: Excellent for understanding how Edge caching (CDNs) interacts with browser caching.

What’s Next?

Now that we understand the Invisible Layer, we can finally move to the Application Layer.

In Part 3, we will be looking at React Query (TanStack Query), to see how to implement an efficient caching system with it.

See you in Part 3.

Part 2: dbt Project Structure &amp; Building Models 📁

2026-02-17 06:45:11

DataEngineeringZoomcamp #dbt #AnalyticsEngineering #DataModeling

Why Model Data? 📐

Raw data is messy and hard to query. Dimensional modeling organizes data into a structure that's:

  • Easy to understand
  • Fast to query
  • Flexible for different analyses

Fact Tables vs Dimension Tables

This is the core of dimensional modeling (also called "star schema"):

Fact Tables (fct_)

  • Contain measurements or events
  • One row per thing that happened
  • Usually have many rows (millions/billions)
  • Contain numeric values you want to analyze

Examples:

  • fct_trips - one row per taxi trip
  • fct_sales - one row per sale
  • fct_orders - one row per order
-- Example fact table
CREATE TABLE fct_trips AS
SELECT
    trip_id,           -- unique identifier
    pickup_datetime,   -- when it happened
    dropoff_datetime,
    pickup_zone_id,    -- foreign keys to dimensions
    dropoff_zone_id,
    fare_amount,       -- numeric measures
    tip_amount,
    total_amount
FROM transformed_trips;

Dimension Tables (dim_)

  • Contain attributes or descriptive information
  • One row per entity
  • Usually fewer rows
  • Provide context for fact tables

Examples:

  • dim_zones - one row per taxi zone
  • dim_customers - one row per customer
  • dim_products - one row per product
-- Example dimension table
CREATE TABLE dim_zones AS
SELECT
    location_id,       -- primary key
    borough,           -- descriptive attributes
    zone_name,
    service_zone
FROM zone_lookup;

The Star Schema ⭐

When you join facts and dimensions, you get a star shape:

                    ┌──────────────┐
                    │  dim_zones   │
                    │  (pickup)    │
                    └───────┬──────┘
                            │
┌──────────────┐    ┌───────┴──────┐    ┌──────────────┐
│  dim_vendors │────│  fct_trips   │────│  dim_zones   │
│              │    │  (center)    │    │  (dropoff)   │
└──────────────┘    └───────┬──────┘    └──────────────┘
                            │
                    ┌───────┴──────┐
                    │ dim_payment  │
                    │    types     │
                    └──────────────┘

Why it's powerful:

-- Easy to answer business questions!
SELECT 
    z.borough,
    COUNT(*) as trip_count,
    SUM(f.total_amount) as total_revenue
FROM fct_trips f
JOIN dim_zones z ON f.pickup_zone_id = z.location_id
GROUP BY z.borough
ORDER BY total_revenue DESC;

dbt Project Structure

A dbt project has a specific folder structure. Understanding this helps you navigate any project:

taxi_rides_ny/
├── dbt_project.yml      # Project configuration (most important!)
├── profiles.yml         # Database connection (often in ~/.dbt/)
├── packages.yml         # External packages to install
│
├── models/              # ⭐ YOUR SQL MODELS LIVE HERE
│   ├── staging/         # Raw data, minimally cleaned
│   ├── intermediate/    # Complex transformations
│   └── marts/           # Final, business-ready tables
│
├── seeds/               # CSV files to load as tables
├── macros/              # Reusable SQL functions
├── tests/               # Custom test files
├── snapshots/           # Track data changes over time
└── analysis/            # Ad-hoc queries (not built)

The dbt_project.yml File

This is the most important file - dbt looks for it first:

name: 'taxi_rides_ny'
version: '1.0.0'
profile: 'taxi_rides_ny'  # Must match profiles.yml!

# Default configurations
models:
  taxi_rides_ny:
    staging:
      materialized: view  # Staging models become views
    marts:
      materialized: table # Mart models become tables

The Three Model Layers

dbt recommends organizing models into three layers:

1. Staging Layer (staging/)

Purpose: Clean copy of raw data with minimal transformations

What happens here:

  • Rename columns (snake_case, clear names)
  • Cast data types
  • Filter obviously bad data
  • Keep 1:1 with source (same rows, similar columns)
-- models/staging/stg_green_tripdata.sql
{{ config(materialized='view') }}

with tripdata as (
    select * 
    from {{ source('staging', 'green_tripdata') }}
    where vendorid is not null  -- filter bad data
)

select
    -- Rename and cast columns
    cast(vendorid as integer) as vendor_id,
    cast(lpep_pickup_datetime as timestamp) as pickup_datetime,
    cast(lpep_dropoff_datetime as timestamp) as dropoff_datetime,
    cast(pulocationid as integer) as pickup_location_id,
    cast(dolocationid as integer) as dropoff_location_id,
    cast(passenger_count as integer) as passenger_count,
    cast(trip_distance as numeric) as trip_distance,
    cast(fare_amount as numeric) as fare_amount,
    cast(total_amount as numeric) as total_amount
from tripdata

2. Intermediate Layer (intermediate/)

Purpose: Complex transformations, joins, business logic

What happens here:

  • Combine multiple staging models
  • Apply business rules
  • Heavy data manipulation
  • NOT exposed to end users
-- models/intermediate/int_trips_unioned.sql
with green_trips as (
    select *, 'Green' as service_type
    from {{ ref('stg_green_tripdata') }}
),

yellow_trips as (
    select *, 'Yellow' as service_type
    from {{ ref('stg_yellow_tripdata') }}
)

select * from green_trips
union all
select * from yellow_trips

3. Marts Layer (marts/)

Purpose: Final, business-ready tables for end users

What happens here:

  • Final fact and dimension tables
  • Ready for dashboards and reports
  • Only these should be exposed to BI tools!
-- models/marts/fct_trips.sql
{{ config(materialized='table') }}

select
    t.trip_id,
    t.service_type,
    t.pickup_datetime,
    t.dropoff_datetime,
    t.pickup_location_id,
    t.dropoff_location_id,
    z_pickup.zone as pickup_zone,
    z_dropoff.zone as dropoff_zone,
    t.passenger_count,
    t.trip_distance,
    t.fare_amount,
    t.total_amount
from {{ ref('int_trips_unioned') }} t
left join {{ ref('dim_zones') }} z_pickup 
    on t.pickup_location_id = z_pickup.location_id
left join {{ ref('dim_zones') }} z_dropoff 
    on t.dropoff_location_id = z_dropoff.location_id

Sources and the source() Function 📥

What are Sources?

Sources tell dbt where your raw data lives in the warehouse. They're defined in YAML files:

# models/staging/sources.yml
version: 2

sources:
  - name: staging           # Logical name (you choose)
    database: my_project    # Your GCP project or database
    schema: nytaxi          # BigQuery dataset or schema
    tables:
      - name: green_tripdata
      - name: yellow_tripdata

Using the source() Function

Instead of hardcoding table names, use source():

-- ❌ Bad - hardcoded path
SELECT * FROM my_project.nytaxi.green_tripdata

-- ✅ Good - using source()
SELECT * FROM {{ source('staging', 'green_tripdata') }}

Benefits:

  • Change database/schema in one place (YAML file)
  • dbt tracks dependencies automatically
  • Can add freshness tests on sources

The ref() Function - Building Dependencies 🔗

This is the most important dbt function!

source() vs ref()

Function Use When Example
source() Reading raw/external data {{ source('staging', 'green_tripdata') }}
ref() Reading another dbt model {{ ref('stg_green_tripdata') }}

How ref() Works

-- models/marts/fct_trips.sql
select *
from {{ ref('int_trips_unioned') }}  -- References the int_trips_unioned model

What ref() does:

  1. ✅ Resolves to the correct schema/table name
  2. ✅ Builds the dependency graph automatically
  3. ✅ Ensures models run in the correct order

The DAG (Directed Acyclic Graph)

dbt builds a dependency graph from your ref() calls:

┌──────────────────┐     ┌──────────────────┐
│ stg_green_trips  │     │ stg_yellow_trips │
└────────┬─────────┘     └────────┬─────────┘
         │                        │
         └──────────┬─────────────┘
                    │
                    ▼
         ┌──────────────────┐
         │ int_trips_unioned│
         └────────┬─────────┘
                  │
                  ▼
         ┌──────────────────┐
         │    fct_trips     │
         └──────────────────┘

When you run dbt build, models run in dependency order automatically!

Seeds - Loading CSV Files 🌱

Seeds let you load small CSV files into your warehouse as tables.

When to Use Seeds

Good use cases:

  • Lookup tables (zone names, country codes)
  • Static mappings (vendor ID → vendor name)
  • Small reference data that rarely changes

Not good for:

  • Large datasets (use proper data loading)
  • Frequently changing data

How to Use Seeds

  1. Put CSV files in the seeds/ folder:
seeds/
└── taxi_zone_lookup.csv
locationid,borough,zone,service_zone
1,EWR,Newark Airport,EWR
2,Queens,Jamaica Bay,Boro Zone
3,Bronx,Allerton/Pelham Gardens,Boro Zone
...
  1. Run dbt seed:
dbt seed
  1. Reference in models using ref():
-- models/marts/dim_zones.sql
select
    locationid as location_id,
    borough,
    zone,
    service_zone
from {{ ref('taxi_zone_lookup') }}

# Module 4 Summary - Analytics Engineering with dbt

2026-02-17 06:44:26

DataEngineeringZoomcamp #dbt #AnalyticsEngineering #DataModeling

Part 1: Introduction to Analytics Engineering & dbt Fundamentals 🎯

What is Analytics Engineering?

The Evolution of Data Roles

Traditionally, there were two main roles in data:

Role Focus Skills
Data Engineer Building pipelines, infrastructure, data movement Python, Spark, Airflow, cloud services
Data Analyst Creating reports, dashboards, insights SQL, Excel, BI tools

But there was a gap! Who transforms the raw data into clean, analysis-ready tables? Enter the Analytics Engineer.

What Does an Analytics Engineer Do?

An Analytics Engineer sits between Data Engineering and Data Analytics:

┌─────────────────┐     ┌──────────────────────┐     ┌─────────────────┐
│  Data Engineer  │ ──► │  Analytics Engineer  │ ──► │   Data Analyst  │
│                 │     │                      │     │                 │
│  • Pipelines    │     │  • Transform data    │     │  • Dashboards   │
│  • Infrastructure│    │  • Data modeling     │     │  • Reports      │
│  • Data movement│     │  • Quality tests     │     │  • Insights     │
└─────────────────┘     │  • Documentation     │     └─────────────────┘
                        └──────────────────────┘

Key responsibilities:

  • 📊 Transform raw data into clean, modeled datasets
  • 🧪 Write tests to ensure data quality
  • 📝 Document everything so others can understand
  • 🔗 Build the "T" in ELT (Extract, Load, Transform)

The Kitchen Analogy 🍳

Think of a data warehouse like a restaurant:

Restaurant Data Warehouse Who accesses it
Pantry (raw ingredients) Staging area (raw data) Data Engineers
Kitchen (cooking happens) Processing area (transformations) Analytics Engineers
Dining Hall (served dishes) Presentation area (final tables) Business users, Analysts

Raw ingredients (data) come in, get processed (transformed), and are served as polished dishes (analytics-ready tables).

What is dbt? 🛠️

dbt stands for data build tool. It's the most popular tool for analytics engineering.

The Problems dbt Solves

Before dbt, data transformation was messy:

  • ❌ SQL scripts scattered everywhere with no organization
  • ❌ No version control (changes got lost)
  • ❌ No testing (errors discovered too late)
  • ❌ No documentation (nobody knew what anything meant)
  • ❌ No environments (changes went straight to production!)

dbt brings software engineering best practices to analytics:

  • Version control - Your SQL lives in Git
  • Modularity - Reusable pieces instead of copy-paste
  • Testing - Automated data quality checks
  • Documentation - Generated from your code
  • Environments - Separate dev and prod

How dbt Works

dbt follows a simple principle: write SQL, dbt handles the rest.

┌─────────────────────────────────────────────────────────────┐
│                     Your dbt Project                        │
│                                                             │
│   ┌───────────────┐    ┌───────────────┐    ┌────────────┐ │
│   │  models/*.sql │───►│   dbt compile │───►│ SQL Queries│ │
│   │  (your logic) │    │   dbt run     │    │ (executed) │ │
│   └───────────────┘    └───────────────┘    └────────────┘ │
│                              │                              │
│                              ▼                              │
│                    ┌──────────────────┐                     │
│                    │  Data Warehouse  │                     │
│                    │  (views/tables)  │                     │
│                    └──────────────────┘                     │
└─────────────────────────────────────────────────────────────┘
  1. You write SQL files (called "models")
  2. dbt compiles them (adds warehouse-specific syntax)
  3. dbt runs them against your data warehouse
  4. Views/tables are created automatically!

dbt Core vs dbt Cloud

Feature dbt Core dbt Cloud
Cost Free (open source) Free tier + paid plans
Where it runs Your machine/server Cloud-hosted
Setup Manual installation Browser-based IDE
Scheduling Need external tool Built-in scheduler
Best for Local development, cost savings Teams, ease of use

💡 For this course: You can use either! Local setup uses DuckDB + dbt Core (free). Cloud setup uses BigQuery + dbt Cloud.