Json-schema-tester is a project mainly written in JAVASCRIPT and RUBY, it's free.
A dead simple JSON schema tester for use with @hoxworth's json-schema
For use with json-schema: https://github.com/hoxworth/json-schema
Requires sinatra and json-schema
Run with "ruby tester.rb", then go to http://localhost:4567 to quickly and easily test your schema against sample data.