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Twitter Open Sources Clutch

Clutch enables developers to write hybrid applications for iOS and to run A/B test experiments on iOS and Android devices.

Twitter has announced the open sourcing of Clutch technology having two main components: Clutch Framework, useful for writing hybrid applications for iOS with Objective-C, HTML and JavaScript, and Clutch A/B Testing for running tests for native iOS and Android applications.

With the Clutch Framework developers can create a native application for iPhone with Objective-C but the UIViewController can contain a ClutchView having HTML/JavaScript components as a sub-view. A bridge will transfer events between the two to be processed where it makes more sense. The documentation recommends that animations, opening modal windows, and sliding operations to be performed natively, while simple text or content changes can be done in JavaScript.

Clutch A/B Testing has two variants:

  • Normal – there are two codebases and the server pushes alternatively one or the other, collecting a set of metrics and reporting how the test performed
  • Data-driven – there is one codebase but it is augmented with configuration data resulting in changes on how the application looks and behaves. Certain metrics are also collected and a report is generated

Clutch A/B Testing has separate SDKs for iOS and Android. The source code is available on GitHub at

A/B Testing is used to compare the effectiveness of two variants of an application, and it is usually employed to determine what the final app should look like before it is made generally available.

Clutch was initially offered by as a service, enabling developers to create applications online. After being acquired by Twitter in August this year, the team promised their users to make available the entire framework to be used locally, which now has happened by being open sourced. The services provided by will end on November 1st, but they say the “libraries are designed to fail gracefully when the service cannot be reached, so your users will never notice a thing.”

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