Liquid is a template engine which was crafted for very specific requirements

• It has to have simple markup and beautiful results. Template engines which don’t produce good looking results are no fun to use.
• It needs to be non-evaling and secure. Liquid templates are made so that users can edit them. You don’t want to run code on your server which your users wrote.
• It has to be stateless. The compile and render steps have to be separate, so that the expensive parsing and compiling can be done once; later on, you can just render it by passing in a hash with local variables and objects.
• It needs to be able to style emails as well as HTML.

Stuff to read, watch, etc.

• Liquid for Programmers
• Liquid for Designers

• Getting Liquid to Work in Rails

• Liquid (screencast)

Who uses Liquid?

• EV-Manager
• Shopify
• Mephisto
• Chameleon
• Cashboard
• Edicy (see also developer documentation)
• Widgetfinger
• Zendesk
• SandwichBoard
• YikeSite
• Simplicant
• 3scale
• Press Publisher
• Canadian Center for Architecture
• Ronin
• …Add yours :)

Why should I use Liquid?

• You want to allow your users to edit the appearance of your application, but don’t want them to run insecure code on your server.
• You want to render templates directly from the database.
• You like Smarty-style template engines.
• You need a template engine which does HTML just as well as emails.
• You don’t like the markup language of your current template engine.