A good API can save you weeks of development. These 30 APIs are either completely free or have generous free tiers that cover personal projects and MVPs. Every entry includes a sample request and rate limit info.

30 Free and Useful APIs Every Developer Should Know

Weather

APIFree TierWhat You Get
Open-MeteoUnlimitedWeather forecasts, historical data. No API key required. Open source.
OpenWeatherMap1,000 calls/dayCurrent weather, 5-day forecast, air pollution data.
WeatherAPI1M calls/monthReal-time, forecast, astronomy, sports, timezone. Very generous.
# Open-Meteo example (no API key needed!)
curl "https://api.open-meteo.com/v1/forecast?latitude=52.52&longitude=13.41¤t_weather=true"

AI & Machine Learning

APIFree TierWhat You Get
OpenAI API$5 credit (expires in 3 months)GPT-4o, GPT-4o-mini. Enough for thousands of requests.
Claude API$5 creditClaude Opus/Sonnet/Haiku. Great for long-context tasks.
Hugging FaceFree tier with rate limitsThousands of open models via Inference API. Text, image, audio.
Cohere100 calls/minEmbeddings, text generation, reranking. Good for RAG pipelines.

Translation & Text

APIFree TierWhat You Get
Google Translate (LibreTranslate)Self-host = unlimitedOpen-source alternative. Host on a $5 VPS for unlimited translations.
DeepL API500,000 chars/monthHighest quality machine translation. EU-based.
LanguageToolFree (self-host)Grammar and style checker. Open source.

Data & Knowledge

APIFree TierWhat You Get
REST CountriesUnlimitedData on all countries: flags, currencies, languages, timezones.
OpenLibraryUnlimitedBook data: covers, authors, editions. Internet Archive project.
PokéAPIUnlimitedAll Pokémon data. Great for learning how to consume REST APIs.
NASA APIs1,000 calls/hourAPOD (Astronomy Picture of the Day), Mars rover photos, Earth imagery.

Images & Media

APIFree TierWhat You Get
Unsplash API50 requests/hourHigh-quality free photos. Attribution required.
Pexels API200 requests/hourFree stock photos and videos. No attribution required.
ImgBBUnlimited (32MB limit)Image upload with auto-generated URLs. Great for quick hosting.

Dev & Infrastructure

APIFree TierWhat You Get
GitHub API60 requests/hour (unauth)Repos, issues, users, gists. Use a token for 5,000/hr.
ipapi1,000/day (or 45/min)IP geolocation. City-level accuracy on free tier.
ExchangeRate-API1,500/monthCurrency conversion rates. Updated daily.

Fun & Niche

APIFree TierWhat You Get
JokeAPIUnlimitedProgramming jokes, dark jokes, puns. Filter by category.
Bored APIUnlimitedRandom activity suggestions. Filter by type and participants.
Dog APIUnlimitedRandom dog pictures by breed. The internet's most important resource.

API Design Tips

  • Cache aggressively — Most free APIs have rate limits. Cache responses so you don't hit them unnecessarily.
  • Use exponential backoff — When you get a 429 (rate limited), wait and retry with increasing delays.
  • Keep keys out of your repo — Use environment variables. Even for free API keys.
  • Fallback gracefully — Free APIs can go down. Your app should still work if the dog picture API is having a bad day.