Diff Checker
Paste two versions of a text and instantly see what was added, removed, or changed between them. Editors, contract reviewers, and developers use diffs to catch every change without re-reading whole documents.
How to use the Diff Checker
- Paste the original text into the left panel.
- Paste the revised text into the right panel.
- Press compare to highlight insertions and deletions side by side.
- Scan the highlighted sections to review each difference.
When the Diff Checker is useful
- Comparing contract or policy revisions before accepting them.
- Reviewing edits between two drafts of an article or thesis chapter.
- Verifying that a translation or transcription kept the original meaning.
- Checking configuration or list files for accidental modifications.
How the Diff Checker works
The comparison aligns both texts line by line and marks spans that exist only in one version, coloring additions and deletions so the eye can follow the edit history. Running the diff locally means unpublished manuscripts, legal text, and internal documents are never transmitted to a third-party comparison service, which is a real risk with many online diff tools.
Limits to keep in mind
Diffs are computed per line, so a small edit that shifts a whole paragraph may highlight more text than the semantic change it represents.
Frequently asked questions
Can I compare code with it?
Yes, any plain text works, including code, config files, and data lists.
Are my documents uploaded anywhere?
No. Both texts are compared inside your browser only.
Does it detect moved paragraphs?
Moved text shows as a deletion plus an addition; the tool does not track moves as a distinct category.
Last reviewed: October 2026.