Couchbase and OpenSearch are both open source tools that can be used for vector search in AI applications. Couchbase is a distributed, multi-model NoSQL document-oriented database that allows developers to store vector embeddings within JSON documents. It supports Full Text Search (FTS) and application-level computations for vector similarity searches. OpenSearch is an open source search and analytics platform with built-in vector search capabilities through its k-NN plugin, supporting both approximate and exact k-NN search methods. Both tools have their strengths and can be used depending on the specific use case, existing tech stack, and performance requirements.