Text Diff Checker
Compare two texts side by side — additions, deletions and changes highlighted.
Free · No sign-up · Runs locally in your browser · Also available in Chinese (中文)
What is Text Diff Checker?
A diff checker compares two versions of text and highlights exactly what changed: lines added, lines removed and lines altered. It is the fastest way to answer 'what is different between these two files?' without reading both end to end.
The comparison is word- and line-aware, so small edits inside a long paragraph are pinpointed instead of the whole paragraph being flagged. Because processing is local, it is safe for confidential content — contracts, credentials in config files, patient notes — that must not be pasted into online services you do not control.
How to use it
- 1Paste the original text into the left panel and the modified text into the right.
- 2Review the highlighted output: additions and deletions are marked inline.
- 3Toggle options such as ignoring whitespace or case when formatting differs but meaning does not.
- 4Copy the merged result or the change list when you are done.
Common use cases
- Comparing two versions of a contract or policy before sending it out.
- Checking what a teammate changed in shared copy or a configuration file.
- Verifying that a translation or rewrite kept every line of the source.
Frequently asked questions
▸Can it compare very large files?
It handles typical document and config sizes smoothly; for multi-megabyte logs a dedicated diff tool on your machine will be faster, but the logic and output are the same.
▸Does it respect line breaks from different systems?
Yes — Windows CRLF and Unix LF line endings are normalized before comparing, so pasting from Notepad and a Linux server still aligns correctly.