Collections of Web Services

General directories (lists of lists)

• An API for Everything
• API search
• API Hub
• list of APIs
• Free web services
• NASA APIs (examples: Astronomy Picture of the Day (APOD service), weather of Mars (Insight service)...)
• collective list of free APIs for use in software and web development
• the full set of generators available at fungenerators.com (lottery number generation, fake id generation, riddles...)
• reddit list of fun APIs

Services for Ecology-related Projects

• Top Air Quality APIs

Miscellaneous Services

• Google natural language understanding
• weather (free plan exists, requires API key)
• COVID 19
• Chart images generator
• SpaceX data
• QR codes generator
• currency
• US stock echanges data (requires a free API key)
• flight tracker and airport timetable data
• take programmatic screenshots of any website
• Food API
• Media API (requires key)
• information about books
• Movie Database
• Movies Database
• Brewery Database
• send SMS
• Spotify API
• Internation Space Station current location
• The internet's biggest collection of open source dog pictures
• cat facts
• Mapbox, alternatve to Google maps
• information about countries

Services for Fun

• Quotes API from They Said So
• Inspiring Expressions
• Affirmations
• random Kanye West quotes
• Dad Jokes
• Chuck Norris facts
• Celebrity Ninjas (free API key required)
• Fun Translations and more (Yoda speak, Pirate talk, etc. but also Braille, Morse...)
• Predict your age from your name
• Pokemon API
• Deck of cards
• Trivia Questions
• Bored API: let's find you something to do
• access NBA related data
• idea for a startup
• "dumbest things Donald Trump has ever said
• random piece of advice
• MARVEL
• Popular memes
• generate HTTP response code images with cats
• Star Wars API
• Interesting number facts
• PurgoMalum: filtering content of unwanted text

A few SDK for popular Web Services

Providing a SDK is a popular way of encouraging the use of your web service. Here are a few examples of web services for which the provider offers such a SDK:

• Google Maps API Web Services: the HTML documentation explaining how to build requests, and the plug-and-play Java client library or Python client library
• eBay services: one of the HTML API reference page, and the plug-and-play SDKs
• Twitter search service: the HTML documentation, and the Python SDK