Disclosure: this post was written with AI assistance and reviewed before publishing. The full dataset is a paid download (link at the end); the list below is free.
Most "free API" lists are years old, and half the links are dead. I took the open-source public-apis list (MIT), added developer and AI free tiers, and checked every documentation URL on 17 October 2026.
Out of 2,230 APIs, 1,944 answered. 847 are live, served over HTTPS, and need no API key at all, which makes them perfect for prototypes, hackathons, bots and AI agents.
Here are 25 well-known ones from that no-key list:
Weather, earth & science
- Open-Meteo: weather forecasts, free for non-commercial use
- USGS Earthquake Hazards: real-time earthquake data
- Sunrise and Sunset: times for any latitude/longitude
- UK Carbon Intensity: Great Britain grid carbon intensity
- GBIF: global biodiversity records
- iNaturalist: citizen-science wildlife observations
- arXiv: research paper metadata
Places & calendars
- REST Countries: country facts
- Nominatim: forward/reverse geocoding (read the usage policy)
- Postcodes.io: UK postcode lookup
- Nager.Date: public holidays for 90+ countries
Money & data
- Frankfurter: exchange rates and time series
- World Bank: world development indicators
- Open Food Facts: food products database
- Universities List: university names and domains
Words, books & culture
- Free Dictionary: definitions, phonetics, synonyms
- Datamuse: word-finding engine (rhymes, "means like")
- Open Library: books and covers
- Crossref: article and book metadata
- Art Institute of Chicago: artworks and images
- Wikipedia / MediaWiki: the encyclopedia
Fun & dev testing
- PokéAPI: Pokémon data
- Open Trivia DB: trivia questions
- Spaceflight News: spaceflight news
- JSONPlaceholder: fake REST API for testing
"No key" doesn't mean "no rules". Read each provider's terms, set a real User-Agent and cache responses.
How I checked them
One GET per URL, a 12-second timeout and an identifying User-Agent, with a second, slower pass for the failures. A 2xx/3xx counts as alive, and so does a 401/403/429, because those mean the server is up but blocks anonymous bots. It's a docs-page check, not an uptime guarantee.
Get the full list
The complete dataset has all 2,230 rows as CSV, JSON and SQLite. That includes the 847-row no-key file, 59 dev and AI free tiers with limits (Groq, Gemini, Mistral, Cloudflare Workers AI, Supabase, Neon and more), and the build script. It's the Verified API Directory 2026 for $12.
AI agents can query it per call instead, over x402 with USDC on Base, at freetier-agent-api.pages.dev.
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