Most APIs require access via API keys (similar to passwords) or other authentication and authorization methods. Keys are a way to protect the provider from malicious users and help them manage their API better.
But for beginners still exploring APIs, keys tend to complicate things. Luckily, there are APIs with zero authentication requirements.
Here are a few of the best, unrestricted, free APIs with no key that you can use for testing. Because they don’t require any keys, you can test the sample URLs out on the address bar of your browser.
Public API for Public APIs
Get a list of any or all public APIs currently cataloged in the project.
Sample API URL:
https://api.publicapis.org/entries
Get information about a specified IP address, such as geological info, company, and carrier name.
Sample API URL:
https://ipinfo.io/161.185.160.93/geo
Get information about a random fake user, including gender, name, email, address, etc.
Sample API URL:
https://randomuser.me/api/
Words API lets you retrieve information about English words, including definitions, synonyms, rhymes, pronunciation, syllables, and frequency of usage. It also can tell you about relationships between words, for instance that “math” has categories like “algebra” and “geometry”, or that a “finger” is part of a “hand”.