Frequently Asked Questions
How do I choose the right API for my project?▼
Consider these factors: (1) Free tier limits - will they cover your development and initial production needs? (2) Pricing at scale - what happens when you grow? (3) Documentation quality - good docs save hours of debugging. (4) Rate limits - can the API handle your expected traffic? (5) Data freshness - is real-time critical or is cached data OK? Our comparison pages cover all these factors for each API category.
Which APIs work without an API key?▼
Several APIs work without signup: Frankfurter (currency exchange), Nominatim (geocoding), goQR.me (QR codes), RDAP (WHOIS lookup), Open-Meteo (weather), DuckDuckGo Instant Answer (search), and Frostbyte's IP and prices endpoints. These are great for prototyping and learning.
What are the best completely free APIs for developers?▼
The best truly free APIs include: Open-Meteo (weather, unlimited, no key), Frankfurter (exchange rates, unlimited, no key), Nominatim (geocoding, free, no key), goQR.me (QR codes, unlimited), RDAP (WHOIS, unlimited), and Let's Encrypt (SSL certificates). Many other APIs offer generous free tiers: AWS SES (62K emails/mo from EC2), Cloudflare (unlimited DNS), and GitHub API (5K req/hr).
How many APIs does this guide compare?▼
This guide compares over 160 individual APIs across 29 categories. Each comparison page includes side-by-side feature tables, pricing at scale, code examples in multiple languages, interactive demos, and decision guides to help you pick the right API.
Are these API comparisons up to date?▼
Yes, all comparisons are updated as of March 2026. We regularly check pricing, rate limits, and feature changes. Each page shows the last updated date. API providers occasionally change their terms, so we recommend verifying current pricing on the provider's website before committing to a paid plan.
Can I use these APIs for commercial projects?▼
Most APIs listed here offer commercial-use licenses on their free tiers, but terms vary. Some restrict commercial use on free plans (check ToS). APIs like Open-Meteo require attribution for non-commercial use. Always review each API's terms of service before using in production. Our comparison pages note any significant usage restrictions.