Markdown Diff Checker — Compare Markdown Files Online
Paste two Markdown documents and instantly see every added line, removed section, and changed text. Ideal for README files, documentation, and content reviews.
Paste text in both panels above to compare
Or to see how it works
Compare README files
When updating a project's README.md, paste the original and the revised version side by side to see exactly what changed — updated installation instructions, new feature descriptions, revised badges, or removed sections. Perfect for reviewing documentation PRs before merging.
Review documentation edits
Technical writers and developers both benefit from seeing exactly which paragraphs, headings, or code examples changed between drafts. Paste your .md files and get a clear, line-by-line comparison with Markdown syntax highlighting preserved.
Audit blog post revisions
Many static site generators and blogging platforms — Jekyll, Hugo, Gatsby, Astro — use Markdown for posts. Compare draft versions, review editor feedback, or audit AI-assisted rewrites to see precisely what text was added, removed, or rephrased.
Markdown syntax highlighting
DiffCheck applies Markdown syntax coloring on top of the diff highlighting. Headings, bold and italic text, inline code, code fences, links, and list items are all color-coded — so you can see document structure while reviewing changes at a glance.
Privacy-first — runs in your browser
Your Markdown content might include draft blog posts, internal documentation, or private product specs. DiffCheck never sends your content to any server. All comparison logic runs locally in JavaScript — safe for confidential drafts and proprietary content.
Spot formatting and whitespace changes
Markdown is sensitive to whitespace — a blank line between paragraphs, trailing spaces for line breaks, and indentation for nested lists all affect rendering. The character-level diff highlights exact whitespace changes within each line, so you can catch unintentional formatting shifts that would otherwise render differently.
How to compare Markdown files online
- 1
Paste your original Markdown
Put the first Markdown document in the left editor — this is your baseline. Works with any Markdown: README files, blog posts, documentation, changelogs, or wikis.
- 2
Paste your revised Markdown
Put the second Markdown document in the right editor. This is what you're comparing against the original — an updated draft, an editor's revision, or the result of a rewrite.
- 3
Read the diff
Green lines were added; red lines were removed. Within changed lines, the exact characters that differ are highlighted more intensely. Markdown is selected by default for syntax coloring.
- 4
Switch views as needed
Use side-by-side view for long documents where you want to see both versions simultaneously, or inline view for a compact sequential change summary. The statistics bar shows total lines added, removed, and unchanged.
Frequently asked questions
What is a Markdown diff checker?
A Markdown diff checker compares two Markdown documents and highlights the differences — added text, removed content, and changed formatting. It's useful for comparing README files, documentation drafts, blog posts, and any content written in Markdown.
Is this Markdown diff tool free?
Yes, completely free with no rate limits and no signup required. All Markdown comparison runs entirely in your browser — your documents never leave your device.
Can I compare GitHub README files?
Yes. Paste two versions of your README.md into the editors and the diff will immediately show every line that changed — updated badges, rewritten descriptions, added sections, or removed content.
Does it highlight Markdown syntax?
Yes. DiffCheck applies Markdown syntax highlighting on top of the diff — headings, bold/italic text, code blocks, links, and lists are all color-coded, making it easy to read document structure while reviewing changes.
Can I use this to review documentation changes?
Absolutely. Paste your original and revised Markdown documents side by side. The diff highlights exactly which sentences, headings, or code examples changed, making it easy to review documentation PRs or content edits.
Is my document content safe to paste here?
Yes. All diff computation runs locally in your browser using JavaScript. Your Markdown content is never sent to any server, never stored, and never logged. Safe for draft content, private documentation, or proprietary README files.