About Stackblade and how the numbers are made
One person keeping careful records of Substack: who's growing, who ranks where, who recommends whom. Here is exactly what I read, how often, and what each number means.
Who it's for
Substack writers who want to know how they're doing next to writers like them. Sponsors who want to see a newsletter's trend before paying for an ad. Anyone who writes about Substack and needs numbers that Substack itself doesn't keep.
What I read
| Source | How often | What I keep |
|---|---|---|
| Category leaderboards (Bestsellers and Rising, top 100, 33 categories) | Once a day | Every position on every read. 4 reads since 31 Oct 2026. |
| Writer profiles (7,649 writers) | Every 3 days; daily for writers on a Pro watchlist | Follower count, Substack's rounded subscriber count, paid band, bestseller badge, the writer's own best leaderboard spot. |
| Recommendation lists (6,392 publications) | Once a week each | Every recommendation given (complete) and the 50 newest received, with Substack's start date. When one disappears from a full list, I record the day. |
Writers get into the reading by appearing on any board, or when a visitor looks them up. Once in, they stay.
How each number is computed
- Followers
- Substack's follower count from the profile, the last reading of the UTC day. Followers follow the writer on Substack; they're not the same as email subscribers.
- 7-day and 30-day change
- Latest reading minus the reading 7 days earlier (30 for the monthly). If that day is missing I use the closest reading 7 to 9 days back (30 to 35) and show the real span. Nothing is shown until that much history exists: the first 7-day numbers appear on Nov 7, 2026.
- Rank and moves
- The position on Substack's board on that read. A move compares two consecutive reads of the same board. A step up is moving into the top 25, the top 10 or to #1, or onto Bestsellers; on Rising only the top 10 and #1 count, because it changes too often.
- Recommended by
- Publications recommending the writer's main publication now. "New in 30 days" counts the ones Substack dates within the last 30 days. Substack lists only a publication's 50 newest recommenders, so for a writer who got more than 50 in that time the count is a floor and shows with a +. Older ones come from the complete lists of the 6,392 publications I read.
- Paid band
- Substack shows paid subscribers as a band (Hundreds, Thousands, Tens of thousands, Hundreds of thousands). The bestseller badge (100, 1,000, 10,000 paid) is a floor where no band shows. I don't estimate exact figures.
- Benchmarks
- Numbers verified writers share (open rate, conversion, revenue band), grouped by category and size. A group shows only when 5 or more writers are in it.
What runs behind it
A Cloudflare Worker that wakes every 3 minutes and does a small, fixed amount of reading: a couple of board pages or a handful of profiles. One request at a time. When Substack answers with 429 or an error, everything pauses for 15 minutes, doubling up to 4 hours. A failed read is never stored as zero. The data sits in a SQLite database at Cloudflare.
What it can't do
- History starts on Oct 31, 2026. Nobody can fill in earlier follower counts or boards; Substack doesn't publish them.
- Writers who never reach a leaderboard are only tracked once someone looks them up.
- Removed recommendations disappear from Substack's lists, so a recommendation that started and stopped before I first read the list is invisible.
- Followers can be bought or inflated like any count. A sudden jump with no new rank or recommendation is worth a second look.
Who runs it
I'm an independent developer. Stackblade isn't affiliated with Substack. Write to me at contact@stackblade.app.