Rails ERD - Generate Entity-Relationship Diagrams for Rails applications

Rails ERD is a Rails plugin that allows you to easily generate a diagram based on your Active Record models. The diagram gives an overview of how your models are related. Having a diagram that describes your models is perfect documentation for your application.

The second goal of Rails ERD is to provide you with a tool to inspect your application's domain model. If you don't like the default output, it is very easy to use the API to build your own diagrams.

Rails ERD was created specifically for Rails 3. It uses Active Record's built-in reflection capabilities to figure out how your models are associated.


Here's an example entity-relationship diagram that was generated by Rails ERD:

Entity-Relationship Diagram

Browse the gallery for more example diagrams.


  • Ruby 1.9.3+
  • ActiveRecord 3.x

Getting started

See the installation instructions for a complete description of how to install Rails ERD. Here's a summary:

  • Install Graphviz 2.22+ (how?)

  • Add gem "rails-erd" to your application's Gemfile

  • Run bundle exec erd


Rails ERD has the ability to be configured via the command line or through the use of a YAML file with configuration options set. It will look for this file first at ~/.erdconfig and then ./.erdconfig (which will override any settings in ~/.erdconfig). The format of the file is as follows (shown here with the default settings used if no .erdconfig is found):

  - content
  - foreign_key
  - inheritance
disconnected: true
filename: erd
filetype: pdf
indirect: true
inheritance: false
markup: true
notation: simple
orientation: horizontal
polymorphism: false
warn: true
title: sample title
exclude: null

Learn more

More information can be found on Rails ERD's project homepage.

If you wish to extend or customise Rails ERD, take a look at the API documentation.

About Rails ERD

Rails ERD was created by Rolf Timmermans (r.timmermans at voormedia.com)

Copyright 2010-2015 Voormedia - www.voormedia.com


Rails ERD is released under the MIT license.