Methodology
StoreTally is a census of five stores: the Chrome Web Store, Microsoft Edge Add-ons, Firefox Add-ons, the Apple App Store (US storefront) and Google Play. It reads only what each store already shows the public, keeps its own history of how those numbers change, and computes growth, ranks and store totals from that history. Every figure here is a third-party measurement, not an official number from the store.
Where the data comes from
| Store | Finding listings | Listing details | Usage figure |
|---|---|---|---|
| Chrome | The store's sitemap | The public listing page | Users, as the store shows them - rounded to one or two significant figures |
| Edge | The store's search API | The store's product-details API | Active installs - exact, but refreshed only occasionally by the store |
| Firefox | The add-ons sitemap | The public add-ons API | Average daily users |
| Apple | The App Store sitemaps | The iTunes Lookup API, US storefront | Rating count - Apple publishes no install figure, so it ranks by ratings |
| Google Play | The Play sitemaps | Play's own web data endpoint | Installs - the exact figure, not the "1M+" range shown on the page |
How often
A crawl cycle runs every 30 minutes and re-reads every listing that has gone stale: Chrome, Edge and Firefox listings once a day, Apple listings every 3 days and Google Play listings every 14 days. New listings are discovered once a day after 02:00 UTC (every 30 days for Google Play, whose sitemap runs to tens of thousands of files). A listing the store no longer serves is marked delisted - its history is kept, not deleted - and is re-checked on a slower schedule in case it returns.
History
Each listing stores its current values plus a history of changes. A change is recorded when the version or last-updated date changes, and when a number moves by a meaningful amount: any change on Chrome (its figures are already rounded), and on the other stores a move of at least 5% that is also at least 50 users or 10 ratings, or an average rating moving by 0.05 stars or more. So that a quiet listing still has an evenly spaced history, the biggest 5,000 listings in each store also get a recorded value once a week whether or not anything moved.
Growth
Growth is measured per listing over four windows: a day, a week, a month and a year. Each window compares today's value with a reading at least one window old, kept on a rotating pair of anchors so the comparison is always between one and two windows back. The change is then scaled to the window - a week's figure measured over nine days is scaled by 7/9 - and reported as a per-window rate.
- A window reports nothing until a listing has a full window of history, and nothing when the gap between readings is more than 2.5 windows (Apple and Google Play are crawled too rarely to have a daily figure at all).
- A percentage needs a starting value of at least 1,000 installs or 100 ratings, so a listing going from 3 to 9 does not read as +200%.
- Chrome installs are rounded, so a listing's install "growth" is really the moment it crosses from one rounded figure to the next. Chrome's install change is therefore reported as observed, not scaled, and its percentage is of that rounding step - small listings crossing a step show very large percentages.
- Edge install counts are exact but the store refreshes them so rarely that a week of them usually reads 0.
- For both, ratings growth - the weekly change in rating count, which is exact and moves by one on every store - is the honest rate, and StoreTally uses it for their momentum figures and growth rankings. It is kept for every store except Apple, whose main figure already is ratings.
Ranks
A listing's rank is the number of live listings in the same store with a strictly higher usage figure, plus one - so listings with equal figures share a rank, which on Chrome's rounded counts means large ties. Category rank is the same within the listing's store category. Once a day every live listing's rank is recorded; the change shown on a listing ("up 2 since ...") compares with the rank recorded 7 to 13 days earlier. Daily rank history is kept for the top 1,000 listings in each store and the top 100 in each category.
Store totals
Once a day StoreTally records how many listings each store has - known (ever discovered), live (crawled and still in the store) and delisted - which is the series behind "live listings over time" on Stats. Listings added and removed per day are derived from when each listing was first seen and when it left the store.
Limits
- Stores change their pages and APIs without notice; a figure can be missing or late while a reader catches up.
- "First seen" is when StoreTally first found a listing, not when it was created - everything found by the first full sweep in September 2026 carries that sweep's date. A real creation date is shown where the store publishes one.
- History starts when StoreTally started: growth windows, ranks and store totals fill in as the census gets older.