Angry Bird
Rovio Chief Executive Mikael Hed stands in front of an Angry Birds poster at his company's offices in Helsinki Reuters

Apple is seeking to put its legal weight behind developers targeted by Lodsys, a so-called patent-troll taking aim at app makers on both Apple's iOS and Google's Android.

Lodsys' patents cover an in-app purchase feature that allows users to upgrade their apps. Lodsys told the app developers it wants a 0.575 percent cut of the app developers revenue. The company sent letters to individual app developers instead looking for the money.

Apple stepped up to Lodsys as it filed a motion with the Eastern District of Texas to intervene as the defendant

The iPhone maker also hit back, filing a counterclaim saying both Apple and its developers could use the technology.

Apple has an interest in property that is at the center of this dispute, namely, its license to the patents in suit and its business with the developers, which depends on their use of products and services that Apple is expressly licensed under the patents in suit to offer them, the filing reads.

Both Lodsys's complaint and its threats to other Apple developers adversely affect the value of Apple's license and its business with the developers.

Lodsys declined to comment.

In a blog that contains a FAQ about the issue, the company said it is seeking payment from app developers because they reap the benefits of the technology Lodsys says it has patents on.

Lodsys originally started sending letters to app developers early May.

The Electronic Frontier Foundation called on Apple to defend the app developers, as many don't have the resources to defend against a patent claim in court.

Like many patent trolls, Lodsys does not make or sell anything, but appears to exist solely to exploit rights in patents that it obtained from another company, Intellectual Ventures, which reportedly owns more than 30,000 patents, the EEF said. Of note, like Lodsys, Intellectual Ventures did not invent the patents at issue.