Compare two Markdown documents in your browser
Enter the original in Before and the revised document in After. Results update automatically when either text area or a whitespace option changes; there is no Compare or Submit button. The tool script parses, diffs, renders, and reads selected files in your browser without submitting document contents.
Review the comparison views
- Block diff compares parsed Markdown blocks and highlights changed words within paired blocks.
- Source diff compares the raw Markdown source line by line.
- Rendered preview shows separate Before and After panels with change highlighting.
The parser recognizes headings, paragraphs, list items, fenced code blocks, blockquotes, tables, and horizontal rules. Similarity is based on the count of paired blocks, not a general document similarity score. The other metrics count Blocks added, Blocks removed, Blocks modified, and Blocks unchanged.
How to compare Markdown files
- Enter the first document in Before and the second in After.
- Paste text, select Upload, or drag a file onto either input wrapper. The file picker accepts
.md,.markdown, and.txtfiles. - Review the automatically updated results in Block diff, Source diff, or Rendered preview.
Control whitespace matching
Use Ignore trailing whitespace, Collapse multiple spaces, and Ignore blank-line differences to change block matching. The first two options are enabled by default. These controls affect block matching only; Source diff still compares raw lines.
Understand comparison limits
Block pairing is not guaranteed item tracking. Tables are compared as whole blocks, and substantial structural changes can limit how blocks pair. The implementation defines no maximum input size, performance threshold, or special large-file handling. Unsupported Markdown syntax may remain plain text or render differently in Rendered preview.
The preview renderer supports headings, paragraphs, lists, fenced code, blockquotes, tables, horizontal rules, bold, italics, inline code, and links. It HTML-escapes source text before applying its supported patterns and neutralizes javascript:, data:, and vbscript: link URLs.
Frequently Asked Questions
How is this different from Compare Text?
Compare Text compares plain prose line by line or word by word without understanding Markdown syntax. This tool parses each document into semantic blocks - headings, paragraphs, list items, tables, and fenced code - so a reordered list item or an edited table cell is reported as that specific block changing, not as an arbitrary run of text.
How is this different from HTML Diff?
HTML Diff compares raw HTML markup and rendered pages. This tool works on Markdown source, parses it into blocks, and renders each version as sanitized HTML in Rendered preview - it is built for Markdown documents like READMEs and documentation pages, not arbitrary HTML pages.
What counts as a block?
Headings (# or underlined), paragraphs, individual list items, fenced code blocks, blockquotes, tables, and horizontal rules. Each is compared as its own unit, so a single edited list item does not get lumped in with the rest of the list.
Is it safe to paste Markdown from an untrusted source?
The rendered preview uses an escape-first renderer: source text is HTML-escaped before Markdown formatting is applied, javascript: and data: links are neutralized, and raw HTML is not passed through unescaped.
Is this tool private?
The tool's parsing, diffing, rendering, and selected-file reading run in your browser; the tool script does not submit the document contents. This describes the tool's processing behavior and is not a page-wide claim about shared site services.