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.
Weather
| API | Free Tier | What You Get |
|---|
| Open-Meteo | Unlimited | Weather forecasts, historical data. No API key required. Open source. |
| OpenWeatherMap | 1,000 calls/day | Current weather, 5-day forecast, air pollution data. |
| WeatherAPI | 1M calls/month | Real-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
| API | Free Tier | What You Get |
|---|
| OpenAI API | $5 credit (expires in 3 months) | GPT-4o, GPT-4o-mini. Enough for thousands of requests. |
| Claude API | $5 credit | Claude Opus/Sonnet/Haiku. Great for long-context tasks. |
| Hugging Face | Free tier with rate limits | Thousands of open models via Inference API. Text, image, audio. |
| Cohere | 100 calls/min | Embeddings, text generation, reranking. Good for RAG pipelines. |
Translation & Text
| API | Free Tier | What You Get |
|---|
| Google Translate (LibreTranslate) | Self-host = unlimited | Open-source alternative. Host on a $5 VPS for unlimited translations. |
| DeepL API | 500,000 chars/month | Highest quality machine translation. EU-based. |
| LanguageTool | Free (self-host) | Grammar and style checker. Open source. |
Data & Knowledge
| API | Free Tier | What You Get |
|---|
| REST Countries | Unlimited | Data on all countries: flags, currencies, languages, timezones. |
| OpenLibrary | Unlimited | Book data: covers, authors, editions. Internet Archive project. |
| PokéAPI | Unlimited | All Pokémon data. Great for learning how to consume REST APIs. |
| NASA APIs | 1,000 calls/hour | APOD (Astronomy Picture of the Day), Mars rover photos, Earth imagery. |
Images & Media
| API | Free Tier | What You Get |
|---|
| Unsplash API | 50 requests/hour | High-quality free photos. Attribution required. |
| Pexels API | 200 requests/hour | Free stock photos and videos. No attribution required. |
| ImgBB | Unlimited (32MB limit) | Image upload with auto-generated URLs. Great for quick hosting. |
Dev & Infrastructure
| API | Free Tier | What You Get |
|---|
| GitHub API | 60 requests/hour (unauth) | Repos, issues, users, gists. Use a token for 5,000/hr. |
| ipapi | 1,000/day (or 45/min) | IP geolocation. City-level accuracy on free tier. |
| ExchangeRate-API | 1,500/month | Currency conversion rates. Updated daily. |
Fun & Niche
| API | Free Tier | What You Get |
|---|
| JokeAPI | Unlimited | Programming jokes, dark jokes, puns. Filter by category. |
| Bored API | Unlimited | Random activity suggestions. Filter by type and participants. |
| Dog API | Unlimited | Random 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.