X just released a major open-source update to its For You algorithm.

The update reveals:

• The actual weights used to rank posts
• How likes, replies, reposts, clicks, watch time, follows, blocks and reports affect rankings
• Systems that decide whether a post is shown, restricted or removed
• The code used to train X’s Phoenix recommendation model
• Synthetic data for running a proof-of-concept training test
• SimClusters, which finds posts from accounts you don’t follow
• A new filter required for Brazil’s 2026 election
• A new “Under the Hood” tool showing labels that may limit an account’s visibility

𝕏 continues to make its algorithm more transparent.