Flex is the ultimate ruby client for elasticsearch. It is powerful, fast and efficient, easy to use and customize. It covers ALL the elasticsearch API, and transparently integrates it with your app and its components, like Rails, ActiveRecord, Mongoid, ActiveModel, will_paginate, kaminari, elasticsearch-mapper-attachments, ... It also implements and integrates very advanced features like chainable scopes, live-reindex, cross-model syncing, query fragment reuse, parent/child relationships, templating, self-documenting tools, detailed debugging, ...