Normalize Markdown without touching fenced code

Markdown Cleaner

Remove trailing horizontal whitespace, repair missing heading spaces, optionally standardize unordered bullets, and compact excessive blank lines while preserving fenced code content. This is a conservative text cleaner, not a complete Markdown parser, formatter, linter, renderer, or CommonMark compliance validator.

01Private by designYour text stays in this browser tab.
02Bounded and responsiveUp to 250,000 characters for bounded local analysis.
03Ready to reuseCopy cleaned Markdown or download a branded MD file.

No text upload to Nirmion

Counting and transformations run locally. Nirmion does not send the text in this workspace to an API.

01 / Input

Paste Markdown and choose conservative cleanup rules

Use source Markdown rather than rendered HTML, then decide whether plus and asterisk bullets become dashes and whether repeated blank lines are compacted. Input is limited to 250,000 characters; lines inside triple-backtick or triple-tilde fences remain unchanged except for the fence line itself.

Markdown sourcePaste up to 250,000 characters. Recognized fenced-code content is preserved.0 / 250 000 charactersUnordered bullet stylePreserve markers or convert simple plus and asterisk bullets to dashes outside fences.Repeated blank linesCompact excessive runs or preserve every physical line.

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Runs in this tab without an API request.

Product guide

Clean formatting noise without reflowing authored code

A narrow rule set is safer than silently reformatting tables, nested lists, inline HTML, reference links, front matter, or code blocks that need parser context. Review the complete result in its destination because automated text rules cannot infer every language, house style, data model, or publishing intention.

Step A

Prepare the input

Paste the complete Markdown section and inspect unclosed code fences first, because a missing closing fence causes later lines to be treated as code.

Step B

Choose the rule

Bullet normalization affects only line-start plus or asterisk markers outside fences. Blank compaction limits long empty runs while preserving paragraph separation.

Step C

Review the output

Review tables, nested lists, hard-break spaces, front matter, and dialect-specific extensions in the destination parser before replacing a source file.

How it works

Fence-aware line cleanup with no Markdown rendering

The cleaner walks physical lines and toggles a fenced-code state at triple-backtick or triple-tilde boundaries. Outside fences it trims trailing tabs and Unicode horizontal spaces, inserts a missing space after one to six heading marks, and optionally maps plus or asterisk bullets to dashes. Blank runs can then be compacted. The operation is linear over at most 250,000 characters and produces at most one million characters; no HTML rendering or script execution occurs. The operation runs in this browser tab, applies explicit bounds before expensive work, and does not send workspace text to a Nirmion API.

Useful when

Prepare documentation for a focused review

Use conservative cleanup when whitespace noise and mixed bullet markers are the known issues, then render the result in the real parser.

Normalize README, knowledge-base, changelog, issue-template, static-site, or documentation snippets before review.
Remove accidental trailing whitespace while preserving indentation and spacing inside fenced code examples.
Standardize simple unordered list markers without applying an opinionated full-document formatter.

Questions answered

Markdown Cleaner questions

Practical boundaries matter with text tools. These answers explain what is measured, what is retained, and when a manual review is still needed.

Does it validate Markdown?

No. It performs documented line cleanup and does not build an abstract syntax tree or report every syntax error.

Will fenced code change?

Content between recognized triple-backtick or triple-tilde fences is preserved. An unclosed or indented dialect-specific fence may not behave as expected.

Can trailing spaces be meaningful?

Yes. Some dialects use them for hard breaks, so review rendered output whenever line-break behavior matters.

Privacy and retention

Your draft stays on your device.

Nirmion performs these operations with browser JavaScript. The workspace does not call the catalogue API with your source text, and completed-job content is kept only in this component memory for re-download.

A downloaded file remains in your browser downloads, device storage, backups, and any location where you share it. Clear or close the page when working on a shared device, and avoid pasting secrets into extensions or third-party clipboard managers.

Tool details

A bounded fence-aware Markdown cleanup pass

Nirmion Markdown Cleaner removes trailing horizontal whitespace, repairs compact heading markers, optionally standardizes simple unordered bullets, and reduces excessive blank lines. Recognized fenced code content is preserved so documentation cleanup does not blindly rewrite examples. The cleaner walks physical lines and toggles a fenced-code state at triple-backtick or triple-tilde boundaries. Outside fences it trims trailing tabs and Unicode horizontal spaces, inserts a missing space after one to six heading marks, and optionally maps plus or asterisk bullets to dashes. Blank runs can then be compacted. This makes the behavior inspectable and repeatable instead of presenting an unexplained result.

Output downloads as text_nirmion_tools_markdown_cleaned.md for source up to 250,000 characters. The page explains hard-break spaces, unclosed fences, parser dialects, tables, front matter, and why the result still needs destination rendering. The operation runs in this browser tab, applies explicit bounds before expensive work, and does not send workspace text to a Nirmion API. Downloading clears the active workspace while the latest three completed results remain available in this tab for re-download.