Free Text Diff Checker that works offline
See how two text versions differ without sending drafts or configuration to a remote comparison service. The report uses a familiar unified style: unchanged lines begin with spaces, removals with minus signs and additions with plus signs.
What this text diff checker does
The comparison uses a longest-common-subsequence algorithm to preserve useful unchanged context. It does not attempt a character-level or semantic rewrite analysis, which makes behavior predictable for source snippets, lists, configuration and prose lines.
How to use the Text Diff Checker
- Enter or paste an original and a changed block of text into the tool.
- Adjust the available options so they match the format and result you need.
- Choose Compare text and review a line report where plus marks additions and minus marks removals before using it.
- Copy or download the result, then clear the page if the input was sensitive.
Common uses
- Comparing configuration before deployment
- Reviewing two revisions of notes
- Finding added or removed list entries
- Checking generated text against an expected fixture
Private processing and offline access
This tool does not submit your input to a conversion server. Processing takes place inside the browser using local JavaScript and standard Web APIs. After the PWA has been installed or cached, the page and its core features remain available without an internet connection. Closing or clearing the page removes unsaved input; the tool does not create an account or cloud history.
Tips for accurate results
- Normalize whitespace first when formatting differences are irrelevant.
- Split very large documents into sections for a faster comparison.
- A moved line may appear as one removal and one addition.
Frequently asked questions
Does this tool upload my data?
No. Text Diff Checker processes its input in the current browser and does not submit it to a conversion API.
What input does the Text Diff Checker accept?
Each side can contain up to 350 lines. The comparison is line based and treats capitalization and whitespace as meaningful differences.
Can I use this tool offline?
Yes. Once the Offline Tools PWA has cached the page, the core feature works without an internet connection.