From Querydsl to Spring Filter: One Syntax, Three Backends

Querydsl is one of those libraries that everyone used for years and then quietly stopped updating. The 5.0 release has been "coming soon" since 2019. The GitHub shows commits but no milestone. The issue tracker has a thread titled "Is Querydsl dead?" with hundreds of comments. It's not dead. But if you're starting a new project in 2026 and you're picking between Querydsl and something that's actively maintained, has Spring Boot 4 support, works with MongoDB and in-memory collections, generates OpenAPI docs automatically, and has companion frontend libraries... well, you see where I'm going. This isn't a "Querydsl bad, Spring Filter good" article. Querydsl pioneered type-safe querying for Java and it deserves credit. But migrations happen, and if you're considering one, here's what the conversion looks like. Side-by-side: basic filtering Querydsl: QCar car = QCar . car ; BooleanExpression filter = car . year . gt ( 2020 ) . and ( car . km . lt ( 50000 )) . and ( car . color . eq ( Color . RED )); List < Car > results = new JPAQuery <>( entityManager ) . select ( car ) . from ( car ) . where ( filter ) . fetch (); Spring Filter (query string): @Filter Specification < Car > spec // URL: ?filter=year > 2020 and km < 50000 and color : 'red' List < Car > results = carRepo . findAll ( spec ); Spring Filter (programmatic builder): FilterNode filter = fb . field ( "year" ). greaterThan ( fb . input ( 2020 )) . and ( fb . field ( "km" ). lessThan ( fb . input ( 50000 ))) . and ( fb . field ( "color" ). equal ( fb . input ( Color . RED ))) . get (); Specification < Car > spec = converter . convert ( filter ); List < Car > results = carRepo . findAll ( spec ); Spring Filter (type-safe builder): FilterNode f = CarFilter . where ( fb ) . year (). greaterThan ( 2020 ) . and () . km (). lessThan ( 50000 ) . and () . color (). equal ( Color . RED ) . build (); Specification < Car > spec = converter . convert ( f ); List < Car > results = carRepo . findAll ( spec ); The type-safe bui