How LinkedIn rebuilt search with AI: 2-tower embeddings replace keyword matching, dwell time over likes

_jaydeepkarale · x · 2026-09-16

A thread by jaydeepkarale breaks down LinkedIn's AI-powered search overhaul. The old keyword engine either returned nothing when queries didn't match all keywords, or matched keywords while missing the intent. The new two-layer design: a retrieval layer combining token-based and embedding-based retrievers (a 2-tower architecture ranking by cosine similarity, with post embeddings precomputed offline in batch), followed by a multi-stage ranking layer. Post quality is scored on on-topic rate and long-dwell time — likes and comments are deliberately excluded since they're easy to farm.

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