APIs list & features
Below is a list of the differents APIs services used on this website. Some of them are from well known websites, other are from open sources providers but nonetheless usefull.
Only a small sample of the potential of thoses APIs is shown here, much more complexity and services can be achieved for all of them.
I will be happy to help you do so.

Publish and analyze Tweets, optimize ads, and create unique customer experiences.
The API return the Tweeter informations for an user and his picked Tweet if any.
Youtube
Used to upload videos, manage playlists and subscriptions, update channel settings, and more.
The API return a dozen of videos for a specific search on Youtube.
TheMovieDB
The API service is for those interested in using movie, TV show or actor images and/or data from TMDB.
The API return an image and an abstract with few informations for a researched movie title.

Flickr
Get members photos and metadata, such as license information, geolocation, people, tags, etc.
The API return a dozen of photos for a specific search on Flickr.
Duckduckgo
Instant Answer API gives free access to many Duckduckgo instant answers like: topic summaries, categories, disambiguation, and !bang redirects.
The API return informations: an abstract, a picture, links, .... for a specific search.

Fixer
Fixer is a simple and lightweight API forcurrent and historical foreign exchange (forex) rates.
The API return the rate and amount of a list of currencies for an amount of Euro.

Yelp
Crowd-sourced local business review and social networking site.
The API return a list of business informations with phostos for a business type and location.
OpenStreetMap
OpenStreetMap is a world map, created by common people and free to use under a free license.
The API return a expandable map pointed on a chosen adress.
Vonage
Vonage (formerly Nexmo), everything to build connected applications, SMS, Voice, Video, Verify, ...
The API send a code by SMS to a given phone number, which the user can verify to simulate a verification by SMS.

OpenWeather
Get Forecast (for 10 days with 3-hour step), Historical, and Current weather maps.
The API return the actual weather for a given city or given latitude & longitude.

Finnhub
Free realtime stocks market data, global company fundamentals, economic data, and alternative data.
The API return the actual value for a given stock symbol(on US market), with its daily evolution.

NewsApi
Breaking news headlines from news sources and blogs across the web.
The API return list of articles by category for a specific country.
Coming ...
New APIs will come later, stay tuned ...