| API | Category | Free tier | No CC | Commercial |
|---|
How to read this
"Free forever" means an ongoing free allowance, not a time-limited trial. "Trial credits" are one-off dollars or a window that expires. "No CC" means you can start without entering a card — the fastest path to a working key for prototypes and side projects. "Commercial" flags whether the free tier is generally okay to ship in a paid product; when in doubt, the provider's terms win.
Found one you like? Many have a full guide here with pricing and step-by-step key setup — see OpenAI, Gemini, Twilio, SendGrid, CoinGecko and the rest. Planning what it'll cost once you outgrow the free tier? Use the API stack cost calculator. Not sure which API to pick for the job? Try the API alternatives finder.
Common free-tier gotchas
Rate limits, not volume caps, are what actually break demos. A "free forever" AI API can still throttle you to a few requests per minute — fine for testing one call at a time, unusable for a batch job or a load test. Read the requests-per-minute number, not just the monthly quota, before you build anything that fans out concurrent calls.
"No credit card" and "free forever" are two separate promises — a provider can ask for no card today and still add one later once you cross a usage threshold (Google Maps' $200/mo credit is the classic example: free in practice for low-traffic apps, but the card is on file from day one). Conversely, some card-required tiers (Mapbox, HERE) never actually charge you if you stay under the cap — the card is there to catch overage, not to gate signup.
Free tiers reset on a rolling calendar month in most cases, not on your signup anniversary — check the provider's billing page if the exact reset date matters for a demo or a monthly cron job. And "non-commercial" free tiers (Hugging Face Inference, NewsAPI, CoinGecko's public demo endpoint, CoinMarketCap's dev plan) are genuinely enforced in their terms — providers do audit and cut off API keys used in shipped commercial products, so treat those as prototyping-only unless you upgrade.
Stacking free tiers for an MVP
A small side project can often run entirely on free tiers if you pick providers that don't compete for the same budget line: Google Gemini or Groq for inference, Resend or SendGrid for transactional email, Stripe or PayPal for payments (no monthly fee either way — you only pay once you have revenue), CoinGecko or Alpha Vantage for market data, and OpenStreetMap/Nominatim if you need geocoding but not Google's UI polish. The API stack cost calculator lets you total up several of these at once and see exactly where the first real bill hits once traffic outgrows the free allowance.