This API helps to query rooms, price, facilities, policities, etc. information from many hotels around the world to create a travelling site/application.
HTTP Cats
An API for the awesome HTTP Cats! Use it in your website to show funny error messages.
IBM Watson API
With IBM Watson, you have everything you need to build, deploy, and manage enterprise-grade AI – on any public, private, or hybrid cloud.
Iconfinder API
Iconfinder is the leading search engine and market place for vector icons in SVG, PNG, CSH and AI format.
IGDB: Video Game Database API
Video Game database on demand! Images, info video and other data you can retrieve trough the rest API
iLoveAPI REST API
Build your own solution for PDF processing. Develop PDF and image tools using iLoveAPI’s powerful REST API. PDF libraries available in multiple languages including PHP, Javascript, Ruby and Node.js.
IMDb
License IMDb’s premier entertainment data on film, TV and celebrities with developer documentation for bulk files and API.
Imgflip API
RESTful JSON API for making memes with Imgflip's meme generator.
Instagram API
Instagram Developer Documentation.
Instamojo API
Instamojo is the easiest Payment Gateway solution for any developer.
IP Address Lookup and Geolocation API
Free IP to geolocation REST API supporting IPv4 or IPv6 GeoIP and reverse IP lookup using JSON and XML in PHP, JavaScript, Node, Python, Java, and more.