The main open-source options are Typesense and Meilisearch for fast, simple search; Elasticsearch, OpenSearch and Solr for large-scale and complex requirements; and Postgres full-text for small sites avoiding new infrastructure. All give you retrieval and none give you a search experience.
| Project | Best at | Watch out for |
|---|---|---|
| Typesense | Speed, typo tolerance, simple ops | Fewer advanced ranking controls |
| Meilisearch | Developer experience, instant search | Scaling large corpora |
| Elasticsearch | Flexibility, ecosystem, scale | Operational weight, licensing |
| OpenSearch | Apache-2.0 fork of Elasticsearch | Same operational weight |
| Solr | Maturity, faceting | Steeper configuration |
| Postgres FTS | Zero new infrastructure | Limited relevance tuning |
| Vector DBs | Semantic retrieval | Needs a keyword partner |
Licence cost is zero; total cost is not. Budget for hosting, upgrades, index maintenance, relevance tuning, the front end, and the analytics layer — and for the fact that all of it needs an owner after the person who built it moves on.
Open source is the right answer when search is core to the product and you have or want search expertise in-house. It is the expensive answer when search simply needs to work.