This is a tool for extension developers tired of the usual test cycle: make a change, create a new extension build, install it in the browser (with wait time and confirmations), restart the browser, test. This extension will receive new extension packages on a TCP port, automatically install them and restart the browser if necessary. All you need to do is send your extension package to this port, e.g. with the wget command line tool:

wget --post-file=extension.xpi http://localhost:8888/

It will be even simpler if you integrate this step into the build script of your extension. Note: The response to this request is always 500 No Content to prevent wget from saving the result, this is not an issue.

Configuration

By default the extension will accept connections on port 8888 with 127.0.0.1 (localhost) as the only address allowed to connect. Connection attempts from other IP addresses will show up in Error Console. To accept connections from other addresses add them to the Accept IP addresses options field. If you do that please keep in mind that IP addresses can be spoofed on unprotected networks (e.g. public WiFi).

Firefox Mobile notes

You can also test your extension on a mobile phone while developing on your desktop, simply send the extension package to the IP address of your phone instead of localhost. Firefox 11/12 with native UI currently has some limitations however:

Bug 696533: Inline options aren't supported yet, you will have to change preferences in about:config manually (preference names start with extensions.autoinstaller.).Bug 717904: If your extension isn't restartless, Add-ons Manager will be broken after the restart. You need to restart the browser again, manually.