dev

Apply Diff

Apply a unified diff (patch) to a text file. Verifies each hunk against the source and fails loudly on a mismatch. The counterpart to Text Diff.

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About Apply Diff

Apply Diff takes a unified diff (a patch) and applies it to a text file, verifying every hunk against the source and failing loudly if anything does not line up. It is the counterpart to Text Diff: one produces the patch, this one applies it. Because it runs in your browser, you can patch sensitive files without sending them to any server.

Category
dev
Input
Accepts: text/plain.
Output
Outputs: text/plain (multiple).
Cost
Free, runs in your browser
Memory
low
Privacy: Apply Diff runs entirely on your device. Files you provide never leave your browser — no uploads, no server, no tracking. The page works offline once loaded.

Common uses

  • Apply a code review patch someone pasted into a chat without setting up git locally
  • Reproduce a colleague's edit on your copy of a config file from the diff alone
  • Verify that a patch still applies cleanly to a file before committing it upstream
  • Apply a small change to a snippet you pasted in, when running the patch tool would be overkill
  • Confirm a hunk fails on a mismatch so you catch a stale or wrong patch early
  • Walk a documentation fix from a unified diff into the original Markdown source

Frequently asked questions

What patch format does it accept?

Standard unified diff format, the same output produced by Text Diff and most git/diff tools.

What happens if the diff does not match the file?

It fails loudly. Each hunk is checked against the source and a mismatch stops the operation rather than producing a corrupt result.

Does my file get uploaded?

No. Both the source text and the patch are processed entirely in your browser.

Is this a full git apply replacement?

It applies unified diffs to a single text input. It is meant for quick, server-free patching, not for managing a whole repository.

What do I get back?

The patched text as plain text, ready to copy or download.

Keywords

  • diff
  • patch
  • apply
  • unified
  • hunk
  • merge

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