Methodology
Sources
We collect the data from three public sources: the Chrome Web Store's sitemap, each extension's listing page, and Google's update service.
The sitemap lists the ID of every item in the store. We read it every day and fetch the listing for any new ID the same day.
An extension's public listing page gives its number of users, rating, version, permissions and other details.
Google's update service reports each extension's current version. We check it every day, and when a new version appears, we fetch the extension's listing again that day. The same answer says whether Chrome's Enhanced Safe Browsing trusts the extension, which we explain on a page of its own.
How often we check
Extensions with 1,000 or more users are checked every week, and all others every month. New extensions get extra checks 7 and 30 days after they're published, and any extension is checked again as soon as a new version appears.
Themes and apps are fetched once, to learn what they are, and aren't tracked after that.
The history starts on 26 September 2026, the day tracking began. Each check adds a point to an extension's charts.
All dates and times on this site and in our data files are in UTC. Depending on where you are, the date in UTC can differ from your local date for part of the day.
Removed, unlisted, hidden and missing extensions
We count an extension as removed as soon as it's missing from a complete daily sitemap and the store no longer offers it for Chrome to install. Its page stays up, with the removal date and the data as we last saw it. If the store lists it again, we check it straight away, and its change log records the return.
If the store still offers an extension that has left its lists, we mark it as unlisted: anyone with a direct link can still install it. We keep checking it as usual, and count it as removed only once the store stops offering it.
Sometimes the store still lists an extension but won't show its page to our server. We don't count these as removed. They're marked as not visible to our crawler and checked again every 30 days.
If the store says it doesn't recognize an ID, we mark it as not found and check it again every 7 days.
Google's flags
Google's update service, which Chrome asks about installed extensions, can attach a flag to an extension: malware, policy violation or potentially unwanted software. Chrome uses these flags to disable the extension. We show the flag as Google gives it, on the extension's page, on the removal lists and in a list of every flagged extension, and its change log records when it appears or goes.
These are Google's flags, not our findings, and Google doesn't publish the evidence behind them. Most removed extensions have no flag, and that doesn't tell us why they left or mean they're safe. We ask about every live and unlisted extension each day, and about removed ones for 10 days after they leave, so a flag can appear a few hours after a removal. If you're the developer and think a flag here is out of date, let us know.
If a page fails to load or can't be read, we try again. A failed fetch never changes an extension's status.
How the figures work
User counts and ratings are the store's own figures, as the listing shows them. Ranks order live extensions by their number of users, and extensions with the same count share a rank. Growth is the number of users gained since a count taken at least 7 or 30 days earlier.
Pages name a developer by the business name the store lists for them, where it comes with a D-U-N-S number, and otherwise by the display name of their store account. Developer pages group extensions by the store's publisher account ID, so a developer with more than one account appears on more than one page.
How our crawler behaves
Our crawler runs on a single server at a modest rate. It follows the store's robots.txt, never logs in, and slows down or stops when the store returns errors.
What we don't collect
We don't copy full descriptions, screenshots or reviews, and we remove developers' contact details before anything is stored. For the developer's email address, we keep only a keyed hash. It lets us group a developer's extensions and notice when the address changes, without revealing it. Pages show when an extension moves to another publisher account or gets a new contact email, and which other accounts show the same email.
Accuracy
The data is collected automatically, so it can be wrong or out of date. Before relying on an important fact, check it against the extension's Chrome Web Store listing. Our terms of use explain this in more detail.