Diff Checker

Compare two texts and see the differences highlighted. Free, runs in your browser.

What Is a Diff?

A diff (short for “difference”) is a comparison between two pieces of text that shows exactly what changed. The concept originates from the Unix diff utility introduced in the early 1970s and is the backbone of every modern version control system, including Git.

When you run a diff, each line is classified as added, removed, or unchanged. This makes it trivial to review edits in code, contracts, configuration files, or any other plain-text document.

Common Uses for Diff Checking

  • Code review — Compare two versions of source code before merging a pull request.
  • Configuration audits — Spot unexpected changes in server configs, YAML files, or .env variables.
  • Content editing — Writers and editors compare drafts to see revisions at a glance.
  • Data validation — Compare exported CSV or JSON files to ensure consistency across environments.
  • Legal documents — Track clause changes across contract versions.

Frequently Asked Questions

Is this diff checker free?

Yes. OGPix Diff Checker is 100 % free with no ads, no sign-up, and no usage limits.

Does my text leave my browser?

No. The entire comparison runs client-side in JavaScript. Your text is never sent to a server, making it safe for sensitive or proprietary content.

What algorithm is used?

We use a Longest Common Subsequence (LCS) algorithm to produce a line-by-line diff — the same foundational approach behind git diff and the classic Unix diff command.

Can I compare files?

You can copy-paste the contents of any text file into the two editors. We plan to add drag-and-drop file upload in a future release.

Is there a size limit?

There is no hard limit, but very large files (over ~50,000 lines) may slow down in the browser due to the O(n×m) nature of the LCS algorithm. For typical documents, results appear instantly.