Open-source recommendation algorithms, X's recent actions are quite transparent and worth learning for peers.

Platform X open-sourced the latest recommendation algorithm for the For You feed on May 15, which integrates content from followed accounts and content discovered through similarity search, using the Grok architecture's Phoenix Transformer for unified scoring.
The algorithm analyzes recent interactions and predicts the probabilities of likes, replies, and shares, providing a final relevance score; the ranking process includes candidate collection, context augmentation, scoring, and diversity adjustment.
The open-source release offers a runnable pipeline, pre-trained models, content understanding services, and an ad blending module, all primarily driven by Transformers.