Free Online Text Compare & Diff Checker
Compare two texts side by side and highlight additions, deletions, and changes.
Differences
No comparison yetPaste two versions and click Compare texts.
About the Text Compare & Diff Checker
This tool compares two versions of a piece of text line by line and shows exactly what changed. The original and revised versions sit side by side, and the result is a table where added, removed, changed, and unchanged lines are marked and counted. It is intended for editors reviewing a revised draft, developers checking a config or code change, and anyone who needs to confirm that only the intended lines moved.
How to use it
- Paste the earlier version into Original text and the newer version into Revised text.
- Click Compare texts. A sample comparison is already loaded when the page opens.
- Read the side-by-side table; the badge above it totals added, removed, changed, and unchanged lines.
- Click Swap to reverse the two sides and compare in the other direction.
- Click Copy diff to copy a plain-text version using + and - prefixes.
A practical example
The default example compares a price change and an added sentence. The third line changes from "Old pricing: $19." to "New pricing: $29.", so it is reported as one changed line, while the extra line at the end is reported as added. If you are reviewing a contract revision, this makes it easy to list every altered clause for a colleague without re-reading both documents in full.
Accuracy, limits, and privacy
Comparison is line-based and exact: case, punctuation, and trailing spaces all count, and blank lines are real lines. A word that changes inside a line marks the whole line as changed rather than highlighting the word. Very large inputs are rejected when the number of lines on one side multiplied by the other exceeds 400,000, which keeps the browser responsive. When a line repeats, the diff may pair occurrences in an order you did not expect. Both texts are processed locally and never leave the page.
Frequently asked questions
Does it ignore whitespace or capitalisation?
No. Lines must match exactly. Different indentation, a trailing space, or a capital letter counts as a change.
Can I compare source code?
Yes. It treats both sides as plain text lines, so it works for code, JSON, CSV, and prose, though it does not understand language syntax.
Why does it refuse a very long comparison?
The tool stops when the two line counts multiply past 400,000, because the comparison becomes slow. Split the text into smaller sections and compare those.
Related tools: Find & Replace Text, Remove Line Breaks, Word Frequency Counter.