This article was originally published on AI Study Room . For the full version with working code examples and related articles, visit the original post. 30 Free and Useful APIs Every Developer Should Know 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. 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.…