Secure Text & Code Diff Checker - Side-by-Side, Merge, Export Patch

Compare text and code securely with side-by-side or merge view. Ignore whitespace/case, highlight changes, and export a standard .patch file—100% local.

Click for theater mode

Version A

Version B

Local-only privacy: your text is never uploaded.

How to Use

  1. Paste the old text into Version A and the new text into Version B.
  2. The diff updates automatically.
  3. Switch to Side-by-Side or Merge View.
  4. Click Export Patch to download a .patch file.

Core Features

  • Side-by-Side & Merge: Switch layouts for review or resolution.
  • Clear Highlights: Additions, deletions, and edits are easy to scan.
  • Ignore Options: Whitespace, case, and comment toggles.
  • Export Patch: Download a standard .patch for Git workflows.
  • Offline Privacy: Runs in your browser—no uploads.

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Calculation Logic

  • Diff computation can be implemented with Myers-style or LCS-based algorithms.
  • Debouncing and size thresholds help protect performance.
  • Merge output can use conflict markers (<<<<<<< / ======= / >>>>>>>).

FAQ

  • Is it free?
    • Yes.
  • Do you upload my code?
    • No. Everything runs locally in your browser.
  • How do I create a .patch file from two snippets?
    • Compare, then click Export Patch to download a standard patch.
  • Is there a diff checker that doesn’t upload sensitive text?
    • Yes—this tool is client-side only.