Paste any Substack URL.
See cadence, gaps, and posting rhythm.
We read the publication's public RSS feed and show you posts per week, the gap between posts, which day of the week it publishes, and post length. Free, no signup.
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Posting cadence
Posts per week over the feed window, computed from the public RSS feed.
Works today, free
Gap analysis
Median gap between posts and the single longest gap, with the dates.
Works today, free
Weekday rhythm
Which day of the week the publication favors for new posts.
Works today, free
Post length estimate
Median word count estimate from the feed's post content.
Works today, free
Recent posts list
The 20 most recent posts with title, date, and link.
Works today, free
Subscriber retention by topic
Needs your subscriber export. Substack has no public API for this.
Needs your subscriber export (waitlist)
What this reads, and what it doesn't
Substack has no public API for subscriber counts, opens, or growth. What is public is each publication's RSS feed (typically the last 15 to 20 posts). We fetch that feed, server-side, and compute cadence statistics from it: how often a publication posts, how long the gaps are, which weekday it favors, and roughly how long each post runs.
We do not have your subscriber list, open rates, or unsubscribe data, and we are not asking for Substack login. Retention by topic needs that subscriber data, which only you have (as a CSV export from your own Substack dashboard). If that is useful to you, join the waitlist above.