Text Diff Checker
Text diff checker — compare two versions of any text and see exactly what changed, line by line. Free tool for reviewing contract edits, copy changes, or code.
The Text Diff Checker compares two blocks of text side by side and highlights exactly what changed between them — additions in green, deletions in red, and unchanged lines in grey. It is the same kind of diff view used in code review tools like GitHub and GitLab, applied to any text content: contracts, copy, configuration files, exported data, or any document where you need to track changes precisely. This free online diff tool runs entirely in your browser with no file upload and no account required.
The most common use case is reviewing contract or document revisions. When a client returns a marked-up version of a contract, pasting both the original and the revised version into the two panels shows exactly which clauses were changed, added, or removed — without having to read every word. The same workflow applies to comparing two drafts of marketing copy, spotting what changed between two versions of a configuration file, or auditing a CSV export to see which records changed between two data pulls.
The diff is calculated using a line-by-line comparison algorithm (longest common subsequence). Lines that match exactly are shown in grey. Lines that were added appear in green. Lines that were deleted appear in red, so you can scan a long document and immediately see which lines changed.
All processing happens client-side in your browser. Neither version of your text is transmitted to any server. This makes the compare text online tool safe to use with sensitive documents — legal agreements, financial statements, confidential configuration files — where you would not want the content leaving your device.
Frequently Asked Questions
- Does it compare character by character or line by line?
The diff is calculated line by line by default. Changed lines are highlighted, and within those lines, the specific changed words or characters are further highlighted for precision.
- Can I diff code as well as regular text?
Yes. The tool handles any text content including code, JSON, HTML, and prose. It does not do syntax highlighting, but the diff itself works correctly on any text.
- Is there a size limit on the text I can compare?
Large texts work fine, though comparing very long documents may be slightly slow on older devices. There is no hard character limit.
- Is there a free text diff checker online?
Yes. Paste the original and revised text into the two panels and it runs a line-by-line comparison instantly. Because it is all client-side, it is also safe to paste in a contract draft or other text you would not want sitting on a third-party server.
- What is a text diff and when is it useful?
A text diff is a comparison between two versions of the same text that highlights what changed between them. It is useful when reviewing contract revisions, comparing two versions of a document, checking copy edits, or seeing what changed in exported data between two exports.