Check a Markdown draft before you paste it into a publishing editor.
One draft, five destination-specific handoffs. Every change and every loss is named, with a link to the dated live test it came from. Your draft never leaves this browser.
Open the checkerNo account, no upload, no AI.
Worked exampleFive destinations
## What survives the paste Markdown is not one format. Every editor keeps a different subset. | Editor | GFM tables | | -------- | ---------- | | Beehiiv | Kept | | Substack | Destroyed |
- WordPressThe post title is not filled by pasting.Action required
- SubstackTables become accessible labeled rows.Review needed
- BeehiivHeadings become native headings.Ready
- XSmall tables become labeled rows, keeping every cell value.Review needed
- LinkedInHeading markers are removed; the first line becomes the opening.Review needed
Same analyzer the tool runs, against rules dated 2026-08-24. Nothing here is hand-written.
Why the five disagree
The editors are not implementing one specification. Beehiiv parses a plain Markdown paste into native blocks and keeps tables. Substack ignores Markdown entirely and needs rich HTML on the clipboard instead. WordPress builds native Gutenberg blocks but never fills the post title. X and LinkedIn render no formatting at all and count the draft against a hard character limit. The same file is therefore correct in one editor and broken in another, and the only way to know which is to check it against each one.
Every rule behind the verdicts above comes from a dated live paste into the real editor, with a screenshot, and each one is linked from the destination page it belongs to. Where no dated test covers a construct, the result says unknown rather than guessing.