sync-spray is an add-on for Firefox that generates "random" data and effectively stress tests the Sync component.

sync-spray works by surfing the web automatically.

Start by going to about:sync-spray. Then, enter a seed URI in the text box and hit the button. A new window with multiple tabs will be opened and the browser will start surfing the web automatically.

When every page has finished loading, the extension will find a random anchor to an http URI and will follow it. If it cannot find one, it will go back in the history.

There are many known issues, particularly with things getting stuck. This can happen when a download is started, etc.

Once you start automatic browsing, it continues indefinitely. You can stop automatic browsing by closing the new window. But, you probably want to exit the entire process. Also, you probably want to run this in a new profile so it doesn't "pollute" a profile you care about.