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kyatchi Catch the mail!

Kyatchi (キャッチ catch) is a light NodeJS port of Mailcatcher. Kyatchi is written on top of the super simple Sinatra-like web framework for NodeJS, ExpressJS. The server and client-side javascript is all written in Coffeescript.

Like Mailcatcher Kyatchi runs a super simple SMTP server which catches any message sent to it to display in a web interface. Run Kyatchi, set your favorite app to deliver to smtp:// instead of your default SMTP server, then check out to see the mail that’s arrived so far.

Kyatchi also sends new messages to the web interface through WebSockets with failover support for ANY browser that doesn’t support Websockets. This is done through the power of the awesome and simple pub/sub library Faye.



  1. npm install kyatchi
  2. npm start kyatchi
  3. Go to
  4. Send mail through smtp://

The source is simple and available on GitHub.


To set up your rails app, I recommend adding this to your environment/development.rb:

        config.action_mailer.delivery_method = :smtp
        config.action_mailer.smtp_settings = { :host => "localhost", :port => 1025 }


Doesn’t matter what programming language/framework you’re using. If it uses smtp to send messages, then Kyatchi will work for you!




I was surprised how quickly I was able to get Kyatchi up and running. We definitely have some very powerful tools at our fingertips right now. A big thanks to all of the authors/contributors of the whole stack used in Kyatchi. I would also like to thank the following people:


I started this project because I’ve been wanting to write something like this for a while, but I am doing this in my free time. If you are so inclined, buy me a cup of cofee, soda, or some nourishment by donating via Amazon Payments.