An extension stream is a collection of extension items about RoboFont extensions.

Multiple extension servers provide extension streams; the Mechanic 2 extension reads data from all linked streams, and builds a single list of available extensions.

Mechanic 2 comes with two pre-configured extension streams:

stream contents
Mechanic free & open-source extensions
Extension Store paid extensions

Other streams and individual extensions can be added using the options in the Settings sheet – click on the gears icon (top right of the Mechanic 2 window) to open it.

Support for multiple extension streams opens some interesting possibilities, such as curated lists of extensions or custom commercial stores…

Adding extension streams

In the Settings sheet, use the +/- buttons in the section extensions json url stream to add/remove extension streams from the list.

The Mechanic 2 extension stream is available from this URL:


Using a local server is also possible:


Adding single extension items

Single extension items can be added using .mechanic files – see Extension Item Format for more information.

In the Settings sheet, use the +/- buttons in the section single extension items to add/remove extensions from the list.

Check for updates on startup

The Settings sheet also has an option to let you choose if Mechanic should check for updates when RoboFont starts up.

Last edited on 01/09/2021