Facebook has today revealed details of the next step in its Internet.org plans – providing extensibility by opening the platform to third-parties.

Announced today in a blog post, the launch of Internet.org as a platform for developers will help the organization be more “transparent and inclusive,” it said.

Underpinning the services Internet.org provides users in developing nations are deals with mobile operators – it’s these that allow people to get access to basic websites and services for no cost up-front.

Developers that want to integrate with Internet.org will need to follow a few guidelines to be considered for inclusion though, such as being optimized for browsing on feature phones as well as smartphones. Services also need to encourage exploration of the wider internet, too.

However, a number of companies have expressed concern (and withdrawn from the program) over the potential for imbalance and whether it lives up to net neutrality rules – with Facebook and a small number of companies providing the service, they could also limit the availability of rival offerings or products to end-users.

Facebook says, however, Internet.org users will have better control over the applications they can use in future and the launch of it as a platform for developers is clearly a nod to acknowledge this.

“These websites are very simple and data efficient, so operators can offer these for free in an economically sustainable way. Websites do not pay to be included, and operators don’t charge developers for the data people use for their services,” it said.

“Because these services have to be specially built to these specifications, we started by offering just a few. But giving people more choice over the services they use is incredibly important and going forward, people using Internet.org will be able to search for and use services that meet these guidelines,” it added.