X open sources ranking algorithm, adds shadowban transparency tool

X has open sourced its ranking algorithm, including the code that powers the "For You" timeline, and is adding a tool that lets users see if their account or posts have been affected by its ranking systems, the company announced on August 13, 2026. The source code is now available on GitHub under the Apache v2 license, and the transparency tool is rolling out to an "Under the Hood" page in the app's settings.

Users who have posted 10 or more times in the past month can download their aggregate stats as a JSON file, which shows any labels applied to their account or posts over the past calendar month. The tool is initially available as a pilot to a test group of accounts at least one year old before a broader rollout. Non-technical users can paste the file into an LLM, point it to X's GitHub repository, and ask for an interpretation.

The release expands X's previous open source efforts to include model configuration, filters, and core ranking system details, making the codebase roughly 10 to 15 times larger than before. According to X's VP of Product Keith Coleman, the code includes the core ranking engine that pulls and ranks posts for any user, as well as systems that filter out potentially problematic content. External researchers familiar with recommendation systems were able to train and run X's Phoenix scoring system using the open source code ahead of the launch.

Coleman said the goal is to let the public assess how posts are distributed, audit the code, and critique it so X can keep improving the system. Developers can submit pull requests to the GitHub repository, and X engineers will consider incorporating updates into the algorithm. However, systems that use Grok to predict rule violations are not included in this release to prevent bad actors from working around the company's rules.

The move addresses long-standing concerns about how X's algorithm influences politics, elections, and the spread of misinformation. Before Elon Musk bought the company, Republicans in Congress alleged that Twitter had "shadowbanned" their posts, a claim the company consistently denied. X has become less transparent in some areas since going private, but the company now reports public numbers around user metrics after merging with SpaceX.

Coleman said he hopes people will submit code that improves the algorithm, making it "not just visible to the public, but also, like, by the public." The company clarified that external researchers trained and ran the Phoenix scoring system themselves but did not get the per-post score.