An iPhone application that attempts to detect whether ISPs are throttling online services is now available on Apple's App Store, despite Apple originally refusing to allow it onto iPhones and iPads.

The Wehe app has been available for iOS at this link since last night. It had already been available for Android on the Google Play store for at least a month.

Wehe tests the speeds of YouTube, Amazon, NBCSports, Netflix, Skype, Spotify, and Vimeo in different ways and uses variances in measured results to judge whether or not traffic is being throttled to your device. But Apple initially refused to let the app into the App Store, telling its creator that "your app has no direct benefits to the user."

Apple quickly changed course after news articles were written about the rejection.

Apple's app store review team "mentioned something about how there are lots of apps that claim to do something they cannot possibly do (e.g., medical diagnosis from sensors that don't exist), and so they have to be careful," Wehe app creator David Choffnes told Ars after the app was allowed on the store.

Although the app can be downloaded now, the testing system's servers may be under heavy load today. We've gotten some error messages and delays and can't seem to finish running any tests.

Understanding differentiation

Choffnes is a Northeastern University professor who researches distributed systems and networking. He's gathering data for a study on Internet providers' treatment of different kinds of Internet traffic. A summary of the data collected so far is available here.

"Our goal is to understand differentiation (e.g., throttling policies) worldwide and how they evolve over time," Choffnes told Ars.

The summary data says 573 users have run 3,355 tests and that 10.7 percent of tests revealed "differentiation." The results may reflect video policies that carriers have disclosed, such as Verizon throttling smartphone videos to 480p or 720p quality, or T-Mobile's "Binge On" video optimization.

We'd hesitate to say any individual results prove the existence of throttling that carriers haven't disclosed publicly. As we noted yesterday, testing whether a carrier is throttling is complicated because online services themselves play a major role in service quality, and numerous other network variables can affect throughput. How each Web service is structured, what content delivery methods or networks they use, the distance from a user to a service's closest CDN node, and other factors can affect speeds.

Choffnes said that his research team took steps to minimize the effects other network variables might have on the results. "We use our own servers for our tests, and we run multiple tests to rule out transient performance issues that would lead to false positives," he said.

Still, the app might provide some interesting and useful information to iPhone and Android users, especially now that the Federal Communications Commission has repealed its net neutrality rules that ban blocking and throttling. (The rules are still in place for at least 60 more days.)

Speed testing services can be used to detect slowdowns before carriers admit to them. In July, Verizon Wireless customers noticed that Netflix's speed test tool appeared to be capped at 10Mbps; Verizon acknowledged the new speed limit after users noticed it and later expanded the video throttling policy across its network.

"I think the important thing is to provide transparency so that users can actually compare ISPs and use knowledge of their policies to make more informed decisions," Choffnes said.