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Text Diff Checker — Compare Two Texts

Paste two versions of any text and instantly see the differences highlighted line by line — additions in green, removals in red. Perfect for comparing drafts, code, contracts, or any two blocks of text. Everything runs in your browser, so nothing is uploaded.

What a diff checker does

A diff checker compares two versions of a text and shows you exactly what changed between them. Instead of squinting at two paragraphs trying to spot the one edited word, you paste both versions and the tool highlights every difference line by line — additions marked one way, removals another. It is the same core idea behind the "track changes" you see in code review and document editing, distilled into a single paste-and-compare step.

When you need to compare two texts

The uses are everywhere once you start noticing them. Writers compare two drafts to see what an editor changed. Developers compare two versions of a config file or a snippet to find what broke. Anyone reviewing a contract compares the version they sent with the version that came back, to catch quietly altered clauses. Students compare their work against feedback. Support teams compare a working and a broken configuration. In every case, the question is the same — what is different? — and scanning by eye is slow and unreliable.

How the comparison works

The tool compares the two texts line by line and finds the longest sequence of lines they have in common, then marks everything else as either added or removed. Lines that appear only in the second text are additions; lines that appear only in the first are removals; lines present in both, in the same order, are unchanged. This line-level comparison is exactly how most version-control diffs work, and it is the most useful granularity for prose, lists, and code alike.

Reading the result

In the output, removed lines (present in the original but not the changed version) are shown in red with a minus sign, and added lines (new in the changed version) are shown in green with a plus sign. Unchanged lines appear in muted gray for context. A short summary at the bottom tells you how many lines were added and removed overall. This color coding lets you see at a glance whether a change was small or sweeping, and precisely where the edits landed.

Because the comparison runs entirely in your browser, both texts stay on your device — nothing is uploaded. That matters when you are comparing confidential documents, contracts, or private code, where sending the content to a server would be a real concern.

Privacy: your text never leaves the browser

All processing happens locally, on your own device. Your text is never sent to servers, which makes the tool safe even for confidential content. When you close the tab, nothing remains stored.

Frequently asked questions

Does the diff checker compare word by word or line by line?
It compares line by line, which is the most useful level for most texts — drafts, lists, config files, and code. Each line is treated as a unit: if any part of a line changes, the whole line shows as removed (the old version) and added (the new version), so you can see both side by side.
Is my text uploaded anywhere when I compare?
No. The entire comparison happens locally in your browser using JavaScript. Neither the original nor the changed text is sent to any server, which makes it safe for comparing confidential documents, contracts, or private code.
Can I compare two versions of code?
Yes. Because it works line by line, it handles code well — paste the old and new versions and you will see exactly which lines were added, removed, or changed. For very large files, the comparison still runs in your browser, limited only by your device's memory.
Why does a single changed word show as a whole changed line?
The tool compares at the line level, so any change within a line marks that entire line as removed (old) and added (new). This is standard diff behavior and makes it easy to see the before and after of each edited line together.