Edmodo hopes to make the move from "app" to "platform," with the opening today of its API to third-party Web developers.

At launch, Edmodo boasts some 35 partners who have already developed apps for the new platform -- these include Mathalicious, Late Nite Labs, Desmos, BrainNook, Aviary and (30) others. Using the Edmodo API, these companies can now connect their own apps to the Edmodo social network, meaning that they can tap into Edmodo's badge functionality, feeds, assignments, grade book and so on. These apps are integrated with Edmodo, in terms of single sign-on, analytics, and -- and this is key for both Edmodo users and app developers -- roles (that is, who's a teacher, who's a student, what grade is the student, who's a parent, who's a principal and so on).

According to Edmodo co-founder and CEO Nic Borg, the ability to integrate other tools with Edmodo has been the biggest request from users -- some 6 million of them at last count, in some 70,000 schools.

That sizable customer base makes the opening of the API incredibly attractive for educational app developers too, who can now tap in and sell their products at the classroom level without having to invest in the sorts of sales and marketing that is often out-of-reach for education startups. As teachers will be able to procure the apps for their own classes through the new Edmodo App Store, it won't be necessary to make a district-level sale.

Borg argues that the Edmodo platform will be able to foster "rapid innovation of content" which is difficult now in part due the challenges of selling to schools and to teachers. The feedback loop is also broken, he adds, as it's difficult for educators to see how students are engaged with the software they use in class and how that ties in to various assignments and discussions.

Today's announcement also marks the first real hint of Edmodo 's revenue strategy. While the company has raised over $15 million in venture capital, it hasn't been clear how it was going to make money as Edmodo accounts are free. Now Edmodo will be able to take a cut of the app sales through its app store. Whether that's enough to make the company profitable depends, of course, on the success of the new app store and platform.  

Borg says that the contents of the app store are teacher-driven, for now, but the startup will recognize schools' and parents' demands for specific apps down the road. The new platform is also just focused on Web apps currently, with connections to mobile apps also coming at a later date.