(This page contains 3 embedded Google Trend charts. Looks like those are pretty brittle and sometimes don't load. If you do not see all 3 charts, hit reload. Is that a known problem with Google Trends?)

The recent advancements in progressive web apps made me curious how the popularity of web apps developed over the last years.

So I was comparing search volume for different app types on Google Trends today. And was surprised to see this:

Why does the search volume for "web app" spike every September?

Zooming in on the last peak, it seems the peak was pretty sharply focused around a few days:

So far, I don't have a theory that explains this effect. If someone comes up with an answer, I will updated this page.

Update: A reader speculated that it might correlate with the release cycle of a popular web framework. I looked at Vue, Angular, React, Django and Laravel but see no resemblence of the September effect.

Update 2: The mystery seems solved. It seems to be related to a FIFA web app:

To create it, I simply subtracted the values for 'fifa web app' from the values for 'web app'. Since Google Trends probably shows something akin to a ranking, this is not perfect and the Fifa effect is still visible. However, it paints a pretty positive trend for the interest in web apps in general.