Mashery recently open-sourced a new interactive API documentation system called Mashery I/O Docs. It’s available from Github.

I/O Docs enables developers to experiment with API calls from within the documentation. You can see it in action at Posterous and WordnikAlibris and Klout (correction: the Posterous and Wordnik APIs were the inspiration for I/O Docs, but don’t use I/O Docs).

Accoring to Mashery’s announcement: ” In surveys that Mashery conducted at SXSW and other events, developers consistently cited poor API documentation as a major obstacle to getting started with an API.” Cutting and pasting keys is also cited as an obstacle, so I/O Docs input keys automatically for logged-in developers.

Mashery competes with Apigee, Programmable Web and others.

Disclosure: Mashery is a ReadWriteWeb sponsor, as is Programmable Web’s parent company Alcatel-Lucent.

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