Here is a list of some APIs I found very useful, I tried to organized them by category. I will be updating this list continually with more APIs and categories. Let me know if you have an API you think I should add to this list, or if you want me to cover a specific category.
APIs
Advertising
- Apple iAd – Generate advertising revenue from your iOS app using iAd API.
- Google AdSense – Free, flexible way to earn money from your websites, mobile sites, and site search results.
- Amazon Mobile Ads – Monetize across platforms with multiple ad formats.
- Facebook Marketing API – Manage ads and campaigns using the Facebook API.
Analytics
- Clicky – Allows you to extract your web site’s traffic data into several formats, making it easy to integrate, analyze, or store your data within your own application.
- Woopra – Real-time website analysis tool that targets customer engagement.
- MixPanel – Analytics for mobile and web which helps you analyze the actions people take in your application.
- IBM Digital Analytics – Web Analytics tool often used by e-commerce websites.
- Open Web Analytics – Provides a way to request and work with your data outside of the OWA reporting interface.
- Google Analytics – Google Analytics provides APIs to collect, configure, and report on user-interactions with your online content.
- Amazon Mobile Analytics – Service for collecting, visualizing, and understanding app usage data at scale.
- Flurry – Yahoo’s Flurry provides you with a number of APIs enabling you to export your data.
- Parse – Download recent data to run your own custom analytics.
- Chartie – Free web API that mines the relevant trend patterns from your signal.
- Zoho Reports API – Build powerful reporting and analytical capabilities into your application.
- Localytics – Interface to Localytics analytics platform.
Captcha
- Google reCAPTCHA – ReCAPTCHA lets you embed a CAPTCHA in your web pages in order to protect them against spam and other types of automated abuse.
Check-In
- Facebook Check-In – A check-in made to a location-based Page.
- FourSquare Check-In – Allows you to check in to a place.
- Yahoo GeoPlanet – Geo-enable your applications using Yahoo GeoPlanet.
- Google Places – Access to Google Places’ API.
- Google BigQuery API – A data platform for customers to create, manage, share and query data. v2
- Google Books API – Lets you search for books and manage your Google Books library. v1
- Google Calendar API – Lets you manipulate events and other calendar data. v3
- Google Monitoring API – API for accessing Google Cloud and API monitoring data. v2beta2
- Google CustomSearch API – Lets you search over a website or collection of websites. v1
- Google Drive API – The API to interact with Google Drive. v3
- Google Fitness API – The Fit API. v1
- Google Geonomics API – Provides access to Genomics data. v1beta2
- Gmail API – The Gmail REST API. v1
- Google Classroom API – The Google Classroom API. v1
- The Google Fonts Developer API. – The Google Fonts API helps you add fonts to any web page. v1
- Google Identity Toolkit API. – Help the third party sites to implement federated login. v1
IoT
- Zetta – An open source platform built on Node.js for creating IoT servers that run across geo-distributed computers and the cloud.
- Temboo SDK – This platform acts as a layer on top of third-party APIs, using code snippets to trigger complex processes that run through their cloud platform.
- Xively – Uses free and open libraries to let you connect different types of hardware, using a variety of languages to their cloud service.
- ThingSpeak – “Internet of Things” application and API to store and retrieve data from things using HTTP over the Internet or via a Local Area Network.
Login Authentication
- Facebook Login for Apps – Secure, fast, convenient way to login in your app/website.
- Twitter Sign-in – Works on websites, iOS, mobile and desktop applications.
- GitHub Authentication – Access to GitHub’s Authentication API.
- LinkedIn – Make it convenient for your users to sign in with their professional identity.
- Google Identity – Build an auth system that will grow with your business and reduce the friction of getting users into your app.
- Instagram – Access to Instagram’s OAuth API.
- PayPal – Enables your customers to sign in to your web site quickly and securely using their PayPal login credentials.
Maps
- Google Maps API – Google Maps APIs are available for Android, iOS, web browsers and through HTTP web services. Clients can be found here.
- Mapbox – Access to MapBox’s API.
- Bing Maps – Bing Maps platform provides multiple API options for your application.
- Amazon Maps API v2 – Add interactive 3D maps, graphics, and custom overlays to your Fire Tablet and Fire phone apps.
- Scribble – The Scribble Maps API is a cross browser, mobile ready, HTML5/JavaScript, interactive map builder.
Social Media
- Instagram – Search photos by location, user, tags, view trending photos, and make custom items.
- Flickr – Search through user Flickr content, contacts, upload or replace photos.
- Google+ – Enables apps to login to Google+ view connections, groups, posts, and contact information.
- LinkedIn – Enables apps to connect to user accounts, data, connections,groups, communications, and social streams.
- Facebook – For ads, games, payments, login, sharing stats, and user data.
- Twitter – Enables an app to interact with most of Twitter’s functions.
- Pinterest – Enables apps to view the most clicked-through or repinned Pins, view related posts, and user profiles.
- Tumblr – Create new ways to use Tumblr with access to content, likes, followers, and drafts.
- FourSquare – Access to FourSquare database and ability to interact with Foursquare users.
- YouTube – Add YouTube functionality to your sites and apps.
- Gravatar – Create profiles and avatars using this web service.
- Weibo – Programmatic access to China’s most popular microblogging site.
- DeviantArt – The largest social networking website for artists and art enthusiasts.
- WeChat – WeChat is a social messaging application that works across different and multiple platform.
- Whatsapp Document Interaction – If your application creates photos, videos or audio notes and you’d like your users to share these media using WhatsApp. #Limited
- Snapchat – PHP library of Snapchat’s private API. #Private
- GoodReads – Allows developers access to Goodreads data in order to help websites or applications that deal with books.
- Telegram – The Telegram API allows you to build your own customized Telegram clients.
- Twitch – The Twitch API enables you to develop your own applications using the rich feature set that Twitch provides.
- Reddit – API to build clients, crawlers, scrapers, and browser extensions.
- Zomato – Zomato APIs give you access to the freshest and most exhaustive information for over 1.5 million restaurants across 10,000 cities globally.
- Delicious – Access to Delicious’s API.
- Vimeo – Access to Vimeo’s API.
- Daily Motion – Build applications centered around DailyMotion.
- EventBrite – The Eventbrite Python SDK makes it trivial to interact with the Eventbrite API.
- WordPress – Access to WordPress’ API.
- Imgur – Imgur’s API exposes the entire Imgur infrastructure via a standardized programmatic interface.
Source Control
- GitHub – Build real-world GitHub applications right from authentication, to manipulating results, to combining results with other service.
- GitHub Gists – Access to GitHub’s Gists API.
- SVN – Collection of modular libraries written in the C programming language.
- Mercurial – Access to Mercurial’s API.
URL Shorteners
- Bitly – Access to Bitly’s API.
- Yourls – Generate or get existing short URLs, with sequential or custom keyword.
- Readability – Shorten long URLs and deliver a great reading view with a single, unique URL using the Shortener API.
Tutorials
- Using APIs Without Programming This tutorial looks at some simple ways you can reverse engineer an organization’s data to figure out URLs where data is held.
- Creating an API-Centric Web App: Here’s a guide detailing how to create an app that centers around API calls.
- REST API Tutorial: A tutorial on the basics of using RESTful web architecture principles.