App.net, the social network started by imeem and Picplz founder Dalton Caldwell, has made its first change to the ‘Developer Incentive Program’ that was introduced last September to reward its top developers. Chief of which sees the total bucket fund that is distributed to app-makers rise to $30,000 per month from an initial $20,000.

Ad-free App.net encourages its users to provide feedback on the large number of apps that have been built for the service. Based on the cumulative scores and a weighting algorithm, the funds are distributed out to developers each month to provide an additional revenue stream — although most developers already make money by charging users to download their apps.

“The stated goal of the App.net Developer Incentive Program is to incentivize the creation of applications that people love…It’s been amazing to see the progress the App.net developer ecosystem has made during these few months,” Caldwell wrote in a post on the App.net blog.

The weighting algorithm also takes usage into account, and it has itself been tweaked since the service recently introduce DM-like messaging (via Omega) and file storage (via a new API). Now usage of these two features has been added to ensure that user activity is accurately accounted for when sharing the pot of money.

In addition to increasing the amount of cash to be shared by its developers — which Caldwell says is “recognition of both the increased number of participating developers and the increased number of paid App.net accounts” — App.net is stipulating that all apps participating in the program must include a privacy policy and terms of service. The team is reaching out to developers to make that happen, while each app must also be used by at least 50 users and should be listed in the App.net directory to qualify.

App.net began allowing users to join the service for free if invited by a paying users last week. Although free users have certain restrictions — they can only follow 40 people, for one — they will be solicited for feedback on apps, but their responses will not count towards the divvying out of the money.

The move looks to be a response to the growth in the number of developers and users, particularly since the free tier was opened. While many developers already draw income by producing apps that are not free, it is likely to be a welcomed addition that further incentivizes their efforts.

I briefly caught up with Bill Kunz, the man behind popular $4.99 iOS app Felix (our review), who gave a brief insight into the change and the value of the program from a developer’s perspective:

I’m thrilled by the changes, which are a part of a sound path forward for the development ecosystem surrounding ADN. Dalton’s description of the program as a “bonus” is how I perceive (and plan for) it too, so I’m encouraged to see that point reemphasized.

“We said that there was a lot to learn and that we would revise it in the future, so the fact we revised it in the various ways we did was based on what we learned,” Caldwell told TNW.

While he didn’t reveal the number of developers involved in the program, the directory currently lists 116 apps for all devices. It seems likely that, given the additional funds in the kitty and the increase in members following the new free user tier, we can expect that number to continue to rise.