Web APIs

This page has examples of easy-to-try-out APIs. i.e. Available to public, free.

There are many other APIs out there apart from public, free ones.

Flickr API

Flickr public feeds (no API key needed).
public content
Simple URLs that look like:
https://api.flickr.com/services/feeds/...
Example of Flickr feed: Latest images tagged with "Paris" as:
- XML feed
- JSON feed

Flickr API (need to login and request an API key to use these).
- Much more advanced functionality than a feed.
- Authentication and read-write ability. Your app can upload photos.
- The REST version of the API gives simple URLs that look like:
  https://api.flickr.com/services/rest/...
Flickr API accepts requests in:

Test of flickr.photos.search API method.

Search for a tag like "paris".
The following links use dummy API key and so do not work. You need to insert your own API key:
- Search on tags: method=flickr.photos.search&tags=TAG&api_key=APIKEY
- Returns JSON
- JSONP call: method=flickr.photos.search&tags=TAG&api_key=APIKEY&jsoncallback=myfn
Returns images with various properties. From these properties you can construct URLs of image home page, various sizes of JPEG, etc.
Each API method has a documentation page and an "API explorer" page at bottom.

No public feeds. Need API key.

Test of search method.

Search for a tag like "paris".
The following links use dummy API key and so do not work. You need to insert your own API key:
- Search on tags: search?part=snippet&q=paris&key=APIKEY
- Returns JSON
- JSONP call: search?part=snippet&q=paris&key=APIKEY&callback=myfn

With the Flickr and YouTube APIs above, you can build a browser app. Does not have to be a standalone app.
Can be a web page with HTML and JS that makes the API call (e.g. using JSONP).
e.g. Can have a web page that in response to some event or user input can search YouTube for videos and return a list of videos to put inside the page without going to a new URL.

Problem: The web page Javascript code contains API key to do JSONP call. API key not secret.
Solution: Set up a simple proxy on your server. This proxy calls the service with the API key (not exposed) and outputs the result. Your Javascript calls the proxy. Only your Javascript can call the proxy (same origin policy). Should be just a few lines of PHP.

Twitter API uses REST, JSON.
To register:
1. dev.twitter.com - login
2. apps.twitter.com - create app
3. Access level - Read only or Read-write
4. Access Token - Create Access Token
Need server-side code:
- This is harder to demo than Flickr and YouTube APIs.
- Unlike Flickr and YouTube, you cannot develop a client-side only application.
- Twitter requires authentication on API calls. Uses OAuth.
- This has to be done server-side, not client-side. (Because otherwise client-side can see the keys.)
Twitter libraries (e.g. to do the authentication on server-side)
- twitter-api-php (PHP library to do the authentication)
- TwitterOAuth (PHP library to do the authentication)
- Tutorial on using "twitter-api-php" PHP library
- Tutorial on using "TwitterOAuth" PHP library

"This Video Has [n] Views".
Thoughtful video about APIs and relying on other services and whether your application will work into the future.