A note on add-on stats this week

Add-on developers who log in to AMO and check their stats dashboard may be very happy to find that their active daily users have increased quite a bit this week (my own add-on reports a 46% increase since last week). I wanted to remind developers how we determine ADU and why it is slightly skewed this week.

By default, Firefox will check an add-on’s updateURL every 24 hours to look for an update. Add-ons that don’t have an updateURL specified default to AMO, which is how we determine how many “active daily users” an add-on has. The number of times an add-on’s GUID was pinged on AMO is approximately how many people were using that add-on that day.

In addition to the 24 hour checks, the same URL is pinged for several other reasons such as manually checking for updates, Firefox installations and upgrades, and installed add-on detection for Rock Your Firefox. Unfortunately, there’s not currently a way to differentiate these types of pings, so they are all counted as active daily users instead of only the scheduled pings. (see bug 392180)

So, this week’s large increase can be attributed to a couple things:

  • Downloads – Most add-ons also had a huge increase in the number of downloads this week. My own add-on went from 3,000 downloads per day to hitting 16,000 on Wednesday. If your add-on’s install.rdf doesn’t say it’s compatible with the Firefox version installed, Firefox will ping AMO to see if there’s a new version or if this version actually is compatible. (This is how you can update your compatibility on AMO without uploading a new version.)
  • Firefox 3 installations – When users upgrade Firefox to a new version of Firefox 2 or to Firefox 3, it will ping AMO for every extension installed to see if there’s a new maxVersion. After that, it displays a list of incompatible add-ons and offers the ability to check for new versions. (Thanks to Dave Townsend for researching this.)

Both of these will result in one or more additional update pings, as the compatibility will still be checked every 24 hours as usual.

And now, some aggregate statistics for your enjoyment:

Total downloads from AMO last Tuesday (6/10) and Wednesday (6/11): 932,072 + 985,229 = 1,917,301
Total downloads from AMO this Tuesday (6/17) and Wednesday (6/18): 2,454,024 + 4,472,336 = 6,926,360

Update pings to AMO from hosted add-ons last Wednesday (6/11): 115,375,160
Update pings to AMO from hosted add-ons this Wednesday (6/18): 141,233,285
(I expect Thursday’s ADU count is a good bit higher than Wednesday’s.)