Text Diff — Compare Two Texts Online

Use this free online text diff tool to compare two blocks of text and instantly see what changed. Paste your original text on the left and the changed text on the right, and the difference checker highlights every added line in green and every removed line in red, line by line. It works great for comparing versions of documents, code snippets, configuration files, notes, or any plain text where you need to spot changes fast. Everything runs 100% in your browser, so your text is never uploaded and stays completely private.

🔒 100% private — files never leave your device

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How to use

  1. Paste your original text into the left box
  2. Paste the changed text into the right box
  3. Read the color-coded diff below: green (+) is added, red (−) is removed
  4. Edit either box and the comparison updates instantly, or press Compare to recompute

Frequently asked questions

Is my text uploaded anywhere?

No. The entire comparison runs locally in your browser using JavaScript, so your text never leaves your device and nothing is uploaded to any server.

How does the text comparison work?

The tool compares the two texts line by line and marks each line as unchanged, added (+, shown in green) or removed (−, shown in red) so you can spot every difference at a glance.

Does the diff update automatically as I type?

Yes. The diff refreshes live whenever you edit either box, and you can also click the Compare button to recompute it at any time.

Is there a size limit on the text I can compare?

There is no fixed limit. Because the comparison happens in your browser, very large texts depend on your device's memory, but typical documents, notes and code files compare instantly.

Can I compare code, JSON or configuration files?

Yes. It works with any plain text, including code, JSON, CSV, logs and config files. Just paste both versions and the line-by-line diff shows what was added or removed.

Does it show word-level or character-level changes within a line?

The comparison is line by line: a changed line appears as one removed line plus one added line. This makes it easy to see which whole lines differ between the two texts.

About this tool

Compare two blocks of text line by line and highlight added and removed lines. Runs entirely in your browser, so your text stays private.

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