Text Diff
Compare two texts and see exactly what changed.
Runs in your browser — your text never leaves your device.
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About this tool
Comparing two versions of something by eye is unreliable in a very specific way: you reliably spot the big rewrites and reliably miss the single changed digit. A diff removes that guesswork by aligning the two texts and marking exactly which lines were added, removed or left alone. This is useful well beyond code, for contract revisions, configuration files, translated copy, exported data, and anywhere you have been handed a new version and told only that something changed. The comparison works line by line and finds the longest sequence of lines the two texts share, so unchanged blocks stay aligned instead of everything after a single insertion being reported as different. You can optionally ignore case or collapse whitespace, which is what you want when comparing reformatted text where the actual content is unchanged. Both texts stay in your browser, which matters when the thing you are comparing is a contract or a config file containing credentials.
How to use it
- Paste the original text on the left and the changed version on the right
- Optionally ignore case or whitespace differences
- Read the result — added lines in green, removed in red
Frequently asked questions
Is my text uploaded to compare it?
No. The comparison runs entirely in your browser, so neither version is transmitted or stored. That makes it safe for contracts, configuration files and anything else you would not paste into an unknown server.
Why does it compare whole lines rather than individual words?
Line comparison is what makes the output readable and what almost every diff tool uses, including version control. A word-level diff of a long document produces a confetti of tiny changes that is harder to scan than the line view.
When should I ignore whitespace?
When something has been reformatted, reindented or re-wrapped and you only care whether the actual content changed. Leave it on when whitespace is meaningful, such as in Python, YAML, or anything where indentation carries structure.
Is there a size limit?
Matching sections at the start and end are trimmed before comparison, so long documents with small edits work fine. The limit applies only to the genuinely differing region, which is capped at two thousand lines — beyond that the comparison would take long enough to freeze the page, so it tells you rather than hanging.