In short: A text diff compares two versions of a text and highlights what was added, removed or changed, line by line or word by word.
About Text Diff Checker
When two versions of a document, config file or code snippet look almost identical, finding the difference by eye is slow and unreliable. A diff checker lines them up and marks every change.
This tool computes a line-level diff using the longest-common-subsequence method (the same idea behind git diff), then highlights the changed words inside modified lines so a single edited word stands out. You can ignore whitespace or case differences when they do not matter. Both texts stay in your browser, which makes it safe for contracts, private configs and unreleased code.
How to use Text Diff Checker
- Paste the original text on the left and the new version on the right.
- Optionally ignore whitespace or case.
- Press Compare.
- Read the result: green lines were added, red struck-through lines were removed, and changed words are marked inside lines.
Examples
In the sample, “jumps” became “leaps”, the full stop became an exclamation mark, and a new last line was added — all three are highlighted.
Paste production and staging config files to spot the one setting that differs.
Frequently asked questions
Is there a size limit?
Texts of tens of thousands of lines compare quickly. Extremely large inputs may take a few seconds, since the comparison runs on your device.
Can I compare files directly?
Open the files in any editor and paste their contents. Both sides support any plain text, including code.
Does it detect moved lines?
A moved line appears as removed in one place and added in another, which is how most line-based diff tools show moves.
Is the comparison private?
Yes. Nothing is uploaded; both texts are compared locally. You can check this yourself: open your browser’s developer tools, switch to the Network tab and use the tool — no request carries your input.
Updated November 2026 · Free, no signup · How we build and test tools