Elasticsearch and OpenSearch both build text analysis, BM25, aggregations, and vector search on Lucene, but licensing, governance, hybrid-search APIs, and managed ecosystems have followed separate paths since the 2021 fork.
Typesense is a search server centered on instant, typo-tolerant keyword search. Collection schemas, field weights, facets and sorting are enough to build site search, with a choice between self-hosting and Typesense Cloud; Chinese fields need locale: zh, and domain terminology may require custom segmentation.
Meilisearch turns application data into fast, typo-tolerant full-text search; the hard parts are index settings, asynchronous tasks, Chinese tokenization, access filters, and tested recovery.