Substack Post Analyzer
Paste a full post to get instant, rule-based feedback on sentence length, paragraph structure, headings, hook, call to action, scannability, and repetition. Free, no signup, nothing leaves your browser.
Paste a post above (or try an example) to see your score.
What this post analyzer actually checks
Eight separate checks run against your pasted text: sentence length, paragraph length, whether subheadings are present at longer lengths, how quickly the opening sentence gets to the point, whether the ending invites a specific action, whether the post is broken into enough paragraphs, whether it uses scannable elements like lists or headings, and whether any single word is noticeably overused. Each contributes points toward a 100-point score.
It checks structure and mechanics - the things a rule-based system can actually measure reliably - not whether the ideas themselves are good or whether the post will convert readers. Two posts with identical structure scores can perform completely differently based on what they actually say.
Questions
What does the Substack Post Analyzer score measure?
Eight structural checks: sentence length, paragraph length, headings, hook (opening sentence), call to action, overall structure, scannability, and word repetition - each worth points toward a 100-point total.
Does a high score mean the post will perform well?
Not necessarily - this checks structure and mechanics, not whether the actual ideas or angle will resonate with readers. A well-structured post on a weak topic can still underperform.
Is this different from the Readability Checker?
Yes - this tool scores 8 structural categories (hook, CTA, scannability, etc.) using word-count heuristics, while the Readability Checker uses the Flesch Reading Ease formula based on sentence length and syllable count specifically.
Does any of my pasted text get saved or sent anywhere?
No - the analysis runs entirely in your browser as JavaScript. Nothing is transmitted, logged, or stored; closing the tab clears it completely.