Free Public Data API Directory 2026
9 free public JSON data APIs covering US salary by city, state tax rates, mortgage rates by metro, renovation costs, electricity rates, college ROI, food nutrition, regex patterns, and AI detection tools. No authentication required. CC-BY 4.0 license — free for commercial and non-commercial use with attribution.
name, source, license, last_updated, total_records, data) plus an array under data. Use any HTTP client (curl, fetch, axios, Python requests). No CORS restrictions.Example fetch (JavaScript)
const res = await fetch('https://salario.io/data/us-salary-by-city-2026.json');
const json = await res.json();
console.log(json.total_records); // 300
console.log(json.data[0]); // top city by median salaryUS Salary by City
300 records · 162KBTop 300 US cities by median salary with hourly wage, cost of living index, unemployment rate
rank, city, state, median_salary_usd, median_hourly_wage_usd, cost_of_living_index, median_home_price_usd, unemployment_rate_pctUS State Income Tax Rates
51 records · 13KB51 states ranked by top marginal income tax rate with progressive/flat/none classification
state, abbreviation, top_marginal_rate_pct, tax_system, has_local_income_taxUS Mortgage Rates by City
300 records · 143KBTop 300 US metros: 30-yr fixed, 15-yr fixed, FHA, VA, jumbo + median home price
city, state, median_home_price_usd, rate_30yr_fixed_pct, rate_15yr_fixed_pct, rate_fha_pct, rate_va_pct, rate_jumbo_pctUS Renovation Costs
222 records · ~85KB222 renovation project types with low/avg/high cost, $/sqft, ROI %, duration, DIY difficulty
name, category, avg_cost_low_usd, avg_cost_mid_usd, avg_cost_high_usd, cost_per_sqft_usd, roi_pct, typical_duration, diy_difficultyUS Electricity Rates by State
51 records · ~12KB50 states + DC residential electricity rate (cents/kWh) with monthly and annual bill estimates
state, cents_per_kwh, monthly_bill_900kwh_usd, annual_bill_10800kwh_usdUS College Major ROI
150 records · 80KB150 college majors: starting/mid-career/late-career salary, payback years, lifetime earnings premium, unemployment
name, category, degree_level, avg_starting_salary_usd, avg_mid_career_salary_usd, roi_payback_years, lifetime_earnings_premium_usdFood Nutrition Database
410 records · 309KBCommon foods with calories, macros, micronutrients per serving
food, calories, protein, carbs, fat, serving_sizeRegex Patterns Library
115 records · 78KB115 production-ready regex patterns: email, URL, phone, validation, security, dev. Battle-tested.
name, category, pattern, flags, language, use_case, test_match, test_no_matchAI Detection Tools
26 records · ~6KBAI detection tools comparison by content type with pricing, accuracy claims, specialties
content_type, tool_name, pricing, accuracy_claim, specialty, badgeLicense & attribution
All 9 APIs are licensed under CC-BY 4.0. Free for commercial and non-commercial use. Attribution required: link to the source domain when redistributing. Government data (EIA electricity rates, BLS-derived data) is in the US public domain.
Updates & changelog
- · April 26, 2026 — Initial release of 9 JSON endpoints
- · Quarterly updates — Salary, mortgage, electricity, renovation costs refresh from primary sources
- · Real-time — Tax rates update when state laws change
- · API stability — Field names will not change without 90-day deprecation notice
License: CC-BY 4.0. Free for commercial & non-commercial use with attribution. No authentication required, no rate limits beyond CDN throttling.