Compare Two Text Files Online

Paste two versions of a text file and instantly see what was added, removed, or changed. Switch between unified and side-by-side views with word-level highlighting. Everything runs in your browser - your files never leave your device.

Diff

Text Diff Checker

LOCAL · Browser-Only

Compare two texts and see the differences highlighted

Original Text

0 lines · 0 chars

Modified Text

0 lines · 0 chars

Ignore whitespaceIgnore caseIgnore line endings

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Quick Start

1Paste the first file into the Original panel
2Paste the second file into the Modified panel
3Click Compare to highlight every difference
4Toggle side-by-side view or export the diff as a .patch file

What This Tool Does

Paste the older version on the left and the newer one on the right and the two are lined up row by row. Inside each changed row the words that actually differ are picked out, so a sentence that lost three words does not read as an entirely new line.

Three toggles decide what counts as a difference. Ignoring line endings is on by default, which stops a file saved on Windows reading as completely different from the same file saved on a Mac. Ignoring whitespace and ignoring case are off by default and are worth switching on when you are chasing a content change rather than a formatting one.

The result can leave as plain text with plus and minus prefixes, or as a proper .patch file with three lines of context around each change, which is the format other tools expect when you want to apply the change somewhere else rather than just read it.

Limits Worth Knowing

Both versions stay in your browser. Nothing is uploaded, which is what makes this usable on text you are not allowed to paste into a hosted service.
Very large pairs of files fall back to a coarser comparison: the matching start and end are found and everything between them is shown as one removed block and one added block.
Word-level highlighting switches off above roughly five million characters of combined input.
Words are split on spaces and tabs, so a change inside a long unbroken string shows as a change to the whole token.
Unified and side by side are the two views. There is no three-way or merge view.

Common Questions

Why does every line look changed?

Usually indentation or line endings. Turn on ignore whitespace, remember that ignoring line endings is already on, and compare again.

Can I save the result?

Yes. Copy it as text, or download it as a .patch file with context lines around each hunk.

Is there a limit on file size?

Uploaded files go through a size check, and very large comparisons drop to a simpler line-level algorithm rather than refusing to run at all.

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Looking for FAQs and advanced options? Visit the full Text Diff Checker page →

What This Tool Does

Limits Worth Knowing

Both versions stay in your browser. Nothing is uploaded, which is what makes this usable on text you are not allowed to paste into a hosted service.

Very large pairs of files fall back to a coarser comparison: the matching start and end are found and everything between them is shown as one removed block and one added block.

Word-level highlighting switches off above roughly five million characters of combined input.

Words are split on spaces and tabs, so a change inside a long unbroken string shows as a change to the whole token.

Unified and side by side are the two views. There is no three-way or merge view.