Query preprocessing for search engines
A flexible framework for rewriting and enriching search queries at the engine level — helping you tune relevance, manage synonyms, and control results without changing application code.
A powerful, extensible query rewriting pipeline
Querqy is an open source framework for query preprocessing in Java-based search engines. It lets you apply powerful rules to incoming queries — rewriting terms, expanding synonyms, boosting or filtering results, and replacing queries entirely — all managed externally without redeploying your application.
The built-in rewriters cover the most common relevance tuning needs: Common Rules for query-dependent rewrites, Word Break for handling compound words, and Replace for direct query substitution. You can also plug in your own rewriters to extend the pipeline.
Rules can be loaded from files, a database, or a rules management UI, making it straightforward for search teams to iterate on relevance without engineering involvement.
Tools built around the Querqy library
A web interface for managing Querqy rewriting rules. Supports query-dependent synonyms, filters, boosting and demotion, rule management per language, multiple deployment targets, and per-tenant rules.
A Docker Compose based reference implementation for e-commerce search using Solr and Elasticsearch. Brings together Querqy, SMUI, and complementary tools so you can get a working search platform up and running quickly.
Guides, articles, and talks
Find us in the #querqy channel on the Search Relevancy Slack.
It's the best place to ask questions, share ideas, and connect with the community.
Querqy.org is an initiative by