API explorers – play with a REST API the easy way

To communicate with a REST API (or other web service API), you need to construct a request, send it over HTTP or HTTPS, then receive and parse the response. When creating an app, you do all that with code. But what if you just want to take a look around the API to see what it offers, before diving into the code? API explorers are your friend.

I’ve been putting together some information for a workshop on API technical writing. It’s been a rewarding exercise, because it’s made me think in a structured, educational way about what I do every day. A section of the workshop deals with various online API explorers that I’ve discovered over an extended period of time. This information is likely to be useful to many people, so I’m sharing it in a blog post.

API explorers offer a handy GUI alternative to a command-line tool like cURL. This blog post introduces the Advanced REST Client, which is a generic GUI for interacting with any REST API, and a few API explorers that interact with specific APIs.

Advanced REST Client

The Advanced REST Client is an add-on for Chrome browser. I find it very useful for sending a request to a REST API and receiving the response.

The Advanced REST Client offers a generic web form that you can use to craft an HTTP request, submit the request, and see the response. The screenshot below shows the Advanced REST Client in a Chrome tab. The top text box contains a request for the Flickr REST API. You can see the URL path and the URL parameters specifying the options needed for this particular request: the method (get public photos), the user ID of the person whose photos you want, and an API key.

(Click the image to see a larger version.)

There are more, similar add-ons for Chrome, such as the REST Console and Postman. I haven’t looked at extensions for other browsers, but I’m guessing there are similar tools for them too.

Explorers for specific APIs

Developers of REST APIs and other web service APIs sometimes offer an API explorer, which people can use to take a look around the API before diving into the code.

The principle is the same as the Advanced REST client: an API explorer provides an online form where you can enter the parameters required for an API request, submit the request, and see the results.

The difference is that an API explorer is written for a specific API, whereas the Advanced REST Client is generic. The explorer therefore knows more about the API that it’s accessing. It can therefore:

• Present specific input boxes for the expected URL parameters and the input data expected in the request body.
• Hide such pesky complexities as user authentication. In many cases, you can sign in as a user of the web service, and the API explorer will create any authentication tokens that you need.

Flickr REST API Explorer

To see Flickr’s API explorer in action, you can experiment with requesting a user’s public photos from Flickr. Follow these steps to use the flickr.people.getPublicPhotos method in the API explorer:

1. Go to this link in your browser: https://www.flickr.com/services/api/explore/flickr.people.getPublicPhotos
   You should see Flickr’s App Garden, showing a form with input fields for the arguments required in the request for public photos.
2. Enter the following values:
   • user_id: Paste in the Flickr user ID of the user whose public photos you wish to retrieve. A user ID is a string of characters with an @ sign in the middle. For example, use your own Flickr user ID or feel free to use mine: 31065906@N08.
   • Leave all the optional arguments empty.
   • Output: Select XML (REST). This is the default option.
   • Authentication: Select Do not sign call. (Flickr does not require authentication for this particular API request.)
3. Click Call Method.
4. Scroll down to see the response. The API explorer returns the response body, and a copy of the request URL.

This screenshot shows the input fields for the flickr.people.getPublicPhotos call:

To find all the methods available in Flickr’s API explorer, go to this web page:  https://www.flickr.com/services/api/

The methods are listed down the right-hand side of the page. For example, to find the method you’ve used earlier:

• Click the link on the words flickr.people.getPublicPhotos. You’ll see a documentation page about the getPublicPhotos method.
• Scroll to the bottom, and click the link to the API Explorer for the method.

Twitter REST API Explorer

Twitter’s REST API requires user authentication for every request. The API explorer is especially useful in this case, because it takes care of the authentication plumbing for you. All you need to do is give the explorer permission to access Twitter’s data via your Twitter username. Twitter uses the OAuth 1.0 protocol to authenticate the user. In this case, you’re the user, because you’re using the API explorer. This will all become clear if you follow the steps below. 🙂

1. Go to the Twitter website and sign in as usual. (You do need a Twitter account to try this exercise.)
2. Go to the Twitter API explorer at Exploring the Twitter API.
3. Click the dropdown arrow under Authentication and select OAuth 1.
4. A popup window appears, titled Request Twitter permissions. If you can’t see it, scroll down the page a bit.
5. Click Sign in with Twitter.
6. A window appears, titled Authorize Apigee’s API Console to use your account?
7. Click Authorize app.
8. You should see a short-lived message saying that you’ll be redirected back to the app. Then you’ll find yourself back in the Twitter API explorer. Under Authentication, you’ll see Twitter-<username> where <username> is your Twitter handle. For example, for me it shows “Twitter-sarahmaddox”.
9. Under Select an API method, you’ll see a list of methods – these are the things you can do with the API. Click /statuses/user_timeline.json in the first set of methods (next to one of the blue “GET” buttons).
10. A new set of panels appears. In the Query panel (the smallish panel near the top of the window), scroll down until you can see the user_id and screen_name fields. They’re right at the bottom of the panel, and not immediately visible. In the screenshot below, I’ve already scrolled down within the Query panel.
11. Enter a Twitter username and screen name. In this screenshot, I’ve entered my own Twitter ID:
    
12. Click Send. (The red button near top right.)
13. A short-lived red-flashing message appears, letting you know the app is working. Then the response appears. If you see a green 200 OK, that means everything went well.
14. Scroll down to see the full response. It’s in JSON format. The top part of it looks like this (but there’s much more):
    

Various Google APIs

The Google APIs Explorer provides a GUI interface for many of the Google APIs, including the Calendar API, the Gmail API, and many more:

Happy exploring!