About Text Diff Checker
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.