Since the closure of Google Reader in early July, Feedly has become the industry leader of RSS feeds. In late May, well before the end of Reader, Feedly had over 12 million registered users, it is very likely that since then that number has grown exponentially and the number of active users have also grown.

One advantage of Google Reader was that there were countless clients and users who could choose the best app for reading and managing feeds. Feedly now offers a similar opportunity, because the news reader provider now opens Feedly cloud API to all interested developers. Feedly promises that a single developer can develop a client for Feedly in less than a week.

Feedly has worked by its own account in the past six months, with 50 developers to finish the work on the open API. In addition to synchronizing RSS feeds, the Feedly team aims to provide developers with tools to manage categories, topics, tags and other elements that can create complete and customizable user experience from many points of view.

“The Feedly cloud API encapsulates not only data access to millions of feeds but also offers a powerful personalization graph.  Categories, feeds, topics, tags, mixes, and more are higher-level concepts that allow users to easily define the slice of the Web they want to consume.  The power of the Feedly cloud is that users can perform this personalization once and access it across many apps. The same personalization graph can power an iPhone reader, a desktop reader, a phone dashboard application, an auto entertainment system, a profile in someone’s favorite fashion hub, or a profile in an enterprise marketing or purchasing app,” the company said in a blog post.

The RSS feed reader provides its backend technology for about 50 RSS services and applications and with the new APIs, Feedly hopes to work with a lot of different applications, like other readers, enterprise applications, vertical panels and vertical communities. Feedly already announced partnership with RSS app makers Nextgen Reader, Reeder, gReader, Press, and Newsify in June, ahead of the introduction of Feedly Cloud. The company is also working with Menere, Pure News Widget, Meego, gNewsReader for BlackBerry 10, Sprout Social, IFTTT and planned to have more developers joining in the weeks ahead.

The API is the same as it is used in Feedly Pro version, first introduced in August this year. The Pro version offers additional features including search of articles, extended customer support, and security by paying a monthly or annual subscription.

One of the most missed features of Google Reader was the possibility of a search among all your feeds. By offering same feature in Feedly Pro and further opening up its API to all interested developers, Feedly is securing its position as number one RSS feeder.

The new APIs information and resources are available here for developers. Developers can also visit Feedly’s page to check out the selection of currently available apps.