In John Lilly’s blog post in November about Firefox market share, he said one of the most important factors for figuring out how Firefox is doing is the health of addons.mozilla.org (also known as AMO). AMO recently hit a few milestones, so I thought an update (or perhaps initial view) of the add-ons community was in order.

Earlier this week, AMO served its 600 millionth add-on download. That’s original downloads, not including updates. We currently have over 4000 add-ons hosted on the site and between 800,000 and 1 million downloads every day. The site has around 4.5 million pageviews per day, not including services hosted on AMO such as update checks and blocklisting.

AMO now receives around 100 million add-on update pings every day. This is similar, but not exactly the same, to the “ADU” number as explained on John’s blog.

The application breakdown of those 100 million update pings looks like this for a particular day (in this case last Wednesday):

That’s over 1 million add-ons used daily in Firefox 3 alphas, betas, and trunk. So, in case you’ve missed our previous requests, please update your add-ons for Firefox 3!

We’re working to make this kind of data available to add-on developers in the near future, so look for a post on the Web Development blog about that soon.