Sonic

Sonic is a lightweight search backend that delivers fast results using a fraction of the resources of Elasticsearch. It's a search index that sits between your database and your users: you push text in, it indexes it, and it returns results fast. Written in Rust, runs in under 20MB of RAM. MPL 2.0 license. Sonic isn't a full search engine. It's a search index and suggest engine. You store your documents elsewhere (database, files) and push text to Sonic for indexing. It gives you search results as IDs, and you look up the full documents yourself. Supports autocomplete and typo tolerance.

Fully free. No paid tier, no cloud hosting. Self-host only.

Setup is simple: single binary, one config file, runs as a daemon. Ops burden is minimal once running. It's designed to be a background service you don't think about.

Solo projects and small apps: Sonic is perfect when you need better-than-SQL search without running a JVM. Medium projects: works well up to a few million documents. The catch: Sonic doesn't do faceted search, filtering, aggregations, or relevance tuning. It's fast text search and autocomplete, nothing more. If you need those features, you need Meilisearch or Typesense. And the protocol is custom (not HTTP REST), which means you need a client library for your language.