Mozilla, the company behind Firefox and Thunderbird, has talked a lot in recent years about the unfair advantages that platforms give to their first-party web browsers. Platform Tilt is a new effort from Mozilla to show how Firefox and other third-party browsers stack up against Chrome on Android, Safari on iPhone, and other platform pairings.

Mozilla said in a blog post, “There’s a long history of companies leveraging their control of devices and operating systems to tilt the playing field in favor of their own browser. This tilt manifests in a variety of ways. For example: making it harder for a user to download and use a different browser, ignoring or resetting a user’s default browser preference, restricting capabilities to the first-party browser, or requiring the use of the first-party browser engine for third-party browsers.”

Mozilla is now outlining these “tilts” in a new “Platform Tilt” issue tracker database, while encouraging other web browsers to publish their concerns in a similar fashion. The main purpose is to call more attention to how platforms like iOS and Windows favor their own web browser over the competition, which is useful information in the various antitrust legal actions against Apple, Microsoft, and other big tech companies.

There are ten issues listed with Apple, including the Apple App Store forbiding third-party browser engines, no option to import browser data on iPhone and iPad from other web browsers, and difficult beta testing. On Android, Mozilla points out it can’t import browser data, some features open Chrome instead of the default web browser, and Google search results on Android are worse.

Mozilla also highlighted three issues with Microsoft. The process for setting the default browser on Windows is still difficult, and some Windows features forcibly open links in Edge instead of the default web browser. Microsoft also reverts the default browser to Edge during some Windows setup interactions. Most of those issues were recently made illegal by the European Union, but Microsoft is free to continue doing them in other regions, like the United States.

The new database is a bit like Mozilla’s WebCompat project, which documents the problems that popular websites have in Firefox and other less-popular web browsers. However, instead of specific sites creating a worse experience for Firefox users, Platform Tilt is about software platforms creating a worse experience.

You can check out the full Platform Tilt database at the source link below. It will likely continue to be updated as Mozilla sorts through its issue trackers.