A Rails engine for drawing your app's ER diagram and operating migrations


  • Rails 7.0, 6.1, 6.0, 5.2, 5.1, 5.0, 4.2, 4.1, 4.0, 3.2, or 3.1

  • Graphviz


Bundle 'erd' gem to your existing Rails app's Gemfile:

gem 'erd', group: :development


Browse at your http://localhost:3000/erd


Show Mode

  • Erd draws an ER diagram based on your app's database and models.

  • You can drag and arrange the positions of each model.

    • Then you can save the positions to a local file db/erd_positions.json, so you can share the diagram between the team members.

Edit Mode

  • You can operate DB schema manipulations such as add column, rename column, alter column, create model (as well as table), and drop table.

  • Then, Erd generates migration files on the server.

  • And you can run each migration on your browser super quickly.


  • Fix buggy JS

  • drop column (need to think of the UI)

  • stop depending on Graphviz

  • tests

  • cleaner code (the code is horrible. Please don't read the code, though of course your patches welcome)

Contributing to Erd

  • Send me your pull requests!


Copyright (c) 2012 Akira Matsuda. See MIT-LICENSE for further details.