structured-filter is a generic Web UI for building structured search or filter queries. With it you can build structured search queries like "Contacts where Firstname starts with 'A' and Birthday after 1/1/1980 and State in (CA, NY, FL)"... It is a full jQuery UI widget, supporting various configurations and themes.
QueryBuilder can be used on advanced search engine pages, administration backends, etc. to build complex queries or filters. It is highly customisable and can be used with many jQuery widgets like autocompleters and sliders.
It outputs a structured JSON of rules which can be easily parsed to create SQL/NoSQL/whatever queries. It can also directly create a SQL WHERE statement.