Online REST API for Testing and Prototyping.
Gorest API is a free Development API that requires OAuth authentication, is served over HTTPS and has unconfirmed CORS support.
Public REST API with realistic fake data for users, posts, comments and todos. Bearer-token auth, JSON or XML, customizable rate limits. Free, 24/7.
Details from gorest.co.in.

Unified API suite · now live
Geocode an address, validate an email, track a flight or pull stock data with one account, one dashboard and one API key.
The Gorest API is provided by Go REST (gorest.co.in). Public REST API with realistic fake data for users, posts, comments and todos. Bearer-token auth, JSON or XML, customizable rate limits. Free, 24/7.
Yes. The Gorest API is listed in the Development category of the public-apis directory, which only includes APIs that are free or have a free tier. Check its documentation for rate limits and paid plans.
Yes. The Gorest API uses OAuth authentication, so you need to register for credentials before making requests.
CORS support for the Gorest API is unknown. Test a request from the browser, and fall back to a server-side call if it is blocked.
Yes. The Gorest API is served over HTTPS, so it's safe to use in production.