8 Free APIs That Are Genuinely Useful (Most Developers Don't Know About #4)

I have tested over 200 APIs in the past year. Most are overhyped, poorly documented, or dead within months. But these 8 are genuinely useful, completely free, and I use them in production. 1. ExchangeRate-API — Real-Time Currency Conversion curl "https://open.er-api.com/v6/latest/USD" What it does: Returns exchange rates for 150+ currencies, updated daily. Why it is great: No API key required for the open endpoint. JSON response, fast, reliable. I use it in a pricing tool that converts SaaS prices to local currencies. Free tier: 1,500 requests/month (open endpoint is unlimited but daily rates). 2. Abstract API — IP Geolocation curl "https://ipgeolocation.abstractapi.com/v1/?api_key=YOUR_KEY" What it does: Returns city, region, country, timezone, ISP, and connection type from any IP. Why it is great: More accurate than most free alternatives. I use it to auto-detect user timezone in a scheduling app. Free tier: 20,000 requests/month. 3. Open-Meteo — Weather Without Signup curl "https://