Check Markdown against 12 markdownlint-compatible rules and get inline fix suggestions. Catches heading hierarchy, trailing whitespace, inline HTML, and more. Free.
Free is enough for most one-off jobs. Pro raises the file and batch caps; Pro + Media unlocks GB-scale streaming and unlimited duration.
Larger files supported on Developer (5 GB CSV) and Enterprise (unlimited). All processing happens in your browser — files never reach a server.
Paste your Markdown or drop a .md file
The linter checks 12 common formatting rules with line-number reporting
Review the report — each violation lists its line number, rule code, and a suggested fix for whitespace, blank-line, and style issues
0 bytes uploaded. Markdown Lint runs entirely in your browser using JavaScript. Your markdown — including any secrets, PII, or proprietary content — never leaves your device. No data is sent to any server.
Twelve rules: MD001 (heading increment), MD009 (trailing spaces), MD010 (hard tabs), MD011 (reversed link syntax), MD012 (consecutive blank lines), MD018 (no space after heading marker), MD019 (multiple spaces after heading marker), MD022 (blank lines around headings), MD025 (single H1), MD031 (blank lines around fenced blocks), MD033 (inline HTML), and MD047 (single trailing newline). The browser tool runs all twelve; the API omits MD001.
No — the tool produces a read-only report. Most whitespace, blank-line, and style violations come with a concrete suggested fix you can apply yourself. Structural violations (multiple H1 headings, reversed link syntax) are flagged but left for your editorial judgement.
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