Text Diff Checker
Compare two texts and find differences instantly. Side-by-side / Unified / Inline views, line/word/char granularity, full whitespace and case control. 100% browser-based.
Encodes both texts in the URL hash. Sensitive content will be visible in the URL.
Your text never leaves your browser. Recent diffs are stored only in localStorage.
FAQ
Does my text leave the browser?
No. All comparison runs client-side using a hand-written Myers diff algorithm. Your texts are never uploaded, logged, or transmitted. The optional Share-via-URL feature only encodes content in the URL fragment when you explicitly turn it on.
What algorithm does it use?
We hand-write the classic Myers O((N+M)D) diff algorithm (Eugene W. Myers, 1986) — the same algorithm Git uses internally. It finds the shortest edit script between two sequences. We do not depend on jsdiff, diff-match-patch, or any other npm library.
When should I use Word or Char granularity?
Line is best for code, configs, and structured text — almost all Git-style diffs. Word is best for natural language (contracts, prose) where you want to see which words changed within a line. Char is for very fine comparisons (typo hunting). Char auto-falls-back to Word when input exceeds 5000 chars to prevent slowdowns.
What are ignore patterns for?
They let you skip noise like timestamps, version numbers, or auto-generated comments. For example, ^Last updated:.*$ would ignore any line starting with 'Last updated:'. Patterns use JavaScript regex syntax.
Is there a size limit?
Files are capped at 5MB (text). There is no line-count limit — we tested up to 100,000 lines on each side. Performance: 10K lines diff in <300ms, 100K lines in ~2s on a modern laptop.
Can I apply the exported patch with git?
Yes. The exported .patch file is in unified-diff format compatible with git apply or patch. Use it to share fixes without sending the full file.
Which languages have syntax highlighting?
JavaScript / TypeScript, Python, Go, Rust, Java, C/C++, Ruby, PHP, SQL, and Shell. We auto-detect by file extension or content heuristics. You can also set the language manually. Highlighting is hand-written with regex (no highlight.js / Prism dependency).
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