Voyage AI builds embedding and reranking models used as the retrieval layer in RAG pipelines, sold as a hosted API and, since February 2025, owned by MongoDB. The acquisition folded Voyage's models into Atlas Vector Search as an automated embedding option, while the standalone API continues to serve any vector store — Pinecone, Qdrant, pgvector, Milvus, Weaviate, Elasticsearch, OpenSearch, and others. In January 2026 Voyage replaced its voyage-3 generation with voyage-4, a mo

Cohere Rerank is a hosted cross-encoder scoring service that sits after a first-stage retriever in a RAG pipeline. It takes a query and a list of candidate documents pulled from a vector store, BM25 index, or hybrid search system, and returns a relevance score for each candidate by running the query and the document jointly through a transformer, rather than comparing precomputed embeddings. The trade-off is architectural: reranking is more accurate than bi-encoder similarity