Most Popular APIs: At Least One Will Surprise You

There are a number of ways to discuss API popularity. One of the common methods ProgrammableWeb has used is by mashups, the number of completed apps. However, there may be a leading indicator before developers have even started writing code. The "track" functionality on ProgrammableWeb lets developers declare an interest in receiving updates on particular APIs. By diving into this data we can see many things. For example, recently developers have loved travel. Overall, social and visual APIs rule.

Top 10 tracked APIs of all time

1. Facebook
No surprise here. The biggest social network is the fabric of many of today's applications.Track this API
2. Google Maps
Long a popular API for mashups, developers are still interested in geographic data and flock to Google's service even after it started charging .Track this API 
3. Twitter
Like Facebook, Twitter is part of many apps. It was also the first external API embedded in iOS .Track this API
4. YouTube
There's nothing like YouTube when you want a repository of engaging content. It's no wonder developers are interested in Google's video service.Track this API

5. AccuWeather
Hardly a household name like the others on this list. Nevertheless, weather is a popular category and this API does serious traffic.Track this API 
6. LinkedIn
The social graph on LinkedIn is very different from Facebook and Twitter. When it comes to business applications, no other API makes as much sense.Track this API 
7. Amazon Product Advertising
The granddaddy of this list, Amazon understood and applied the power of APIs early on. Its popularity with developers may also be related to paying them when users make purchases.Track this API 
8. Pinterest
Developers have been very interested even before there was a Pinterest API Now that it finally launched, interest has waned a little, but it's solidly in the top 10.Track this API 
9. Flickr
Still an excellent source of visual content, Flickr is a perennial mashup favorite, too.Track this API
10. Google Talk
It's almost hard to remember how proprietary instant messaging was before Google Talk came along and supported XMPP. The open standard and vast Google network clearly appeals to developers.Track this API

Honorable mentions

There are another three weather APIs in the top 20: Weather ChannelTrack this API, Weather UndergroundTrack this API and Yahoo WeatherTrack this API. Also, a couple of messaging APIs (MSN Messenger, Skype), a couple of travel APIs (Kayak, Yahoo Travel), two delivery companies (FedEx, DHL) and foursquareTrack this API round out the popular APIs.

Recently popular: Developers love travel

Among the APIs developers have tracked recently is a combination of the big names from the top 10, travel services and a few outliers.

Travel has a rich API history. Long before we called it an API, the travel industry had a network to connect airlines and agents. Although it's always been a popular category, perhaps travel is poised for more growth in 2014—there are a handful of other travel APIs just outside the top 10 recently tracked APIs. What's your favorite API on this list? Which ones surprised you? Adam DuVander is Developer Communications Director for SendGrid and Contributing Editor at ProgrammableWeb. Previously he edited this site and wrote for Wired. You can follow him on Twitter.

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