New web APIs can be found on API marketplaces and API directories. API marketplaces are open platforms where anyone can list an API for sale. API directories are controlled repositories regulated by the directory owner. Expert API designers may assess and test a new API before adding it to their directory.
Some popular API websites include:
Rapid API – The largest global API market with over 10,000 public APIs and 1 million active developers on site. RapidAPI allows users to test APIs directly on the platform before committing to purchase.
Public APIs – The platform groups remote APIs into 40 niche categories, making it easier to browse and find the right one to meet your needs.
APIForThat and APIList – Both these websites have lists of 500+ web APIs, along with in-depth information on how to use them.