Restwords

https

Use Restwords to temporarily store XML, HTML, JSON, and TWIML.

Sqlify API

https

Transform and convert from and to common data formats

PageCDN API

https

Public CDN API for opensource javascript, CSS and fonts libraries.

Tardigrade Object Storage

https

API for Services Built on the Decentralized Storj Network

LectServe

https

Protestant liturgical calendar

Holidays

https

API for obtaining information about holidays.

Google Calendar

https

Display, create and modify Google calendar events

Hebrew Calendar

https

Convert between Gregarian and Hebrew, fetch Shabbat and Holiday times, etc.

Russian Calendar

https

Check if a date is a Russian holiday or not

Nager.Date

https

Public holidays for more than 90 countries

Calendarific

https

Calendarific is a simple way to get all holidays for any country in the world via a JSON API

Festivo Holiday API

https

Public holiday API service for several supported countries.

Eventbrite

https

Search events, attractions, or venues with the Eventbrite.

Ticketmaster

https

Search events, attractions, or venues with the Ticketmaster API.

Google Books

https

Google Books is our effort to make book content more discoverable on the Web

Bhagavad Gita

https

The Bhagavad Gita API allows a web or mobile developer to use the Bhagavad Gita text in their web or mobile application(s).

Penguin Publishing

https

Books, book covers, and related data

LibGen

https

Library Genesis has an API, but the only documentation is a forum thread in Russian. So this is an English-language guide to using the LibGen API.

Codeship

https

Codeship is a Continuous Integration Platform in the cloud

Travis CI

https

Sync your GitHub projects with Travis CI to test your code in minutes

CircleCI

https

Automate the software development process using continuous integration and continuous delivery

Icons8

https

Access icons8 collection with their API

Harvard Art Museums

https

The Harvard Art Museums API is a REST-style service designed for developers who wish to explore and integrate the museums’ collections in their projects.

Behance

https

Access the data behind millions of projects and works-in-progress, across all creative fields, client, brand, location, and much more!

Cooper Hewitt, Smithsonian Design Museum

https

Cooper Hewitt, Smithsonian Design Museum Collections provides a REST-ish style application programming interface (API) for developers to use in their products and services

Iconfinder

https

Use Icon Finder API to search icons by name.

The Color API

https

Pass in any valid color and get conversion into any other format, the name of the color, etc

Google Safe Browsing

https

Safe Browsing is a Google service that lets client applications check URLs against Google's constantly updated lists of unsafe web resources.

VirusTotal

https

The VirusTotal API lets you upload and scan files or URLs, access finished scan reports and make automatic comments without the need of using the website interface.

Web Of Trust (WOT)

https

Developers can build web services on top of the WOT API. Search engines, information security companies, social media, and other industries can benefit from reputation data to enhance user experience.