🆚 Text Diff Checker — Compare Two Texts Online Free
Instantly compare two texts line by line — free, runs entirely in your browser with no file uploads or account required, and works offline.
Original
Modified
Diff Result
Enter both texts above, then click Compare.
About
Paste your original and modified texts into the two panels and click Compare to see every addition, deletion, and unchanged line highlighted in color. The diff algorithm uses LCS (Longest Common Subsequence) for accurate line-level comparison. Because everything runs client-side in JavaScript, your text never leaves your device — making this tool safe for confidential code, contracts, or private documents.
How to use
- Paste the original text into the left 'Original' panel.
- Paste the modified text into the right 'Modified' panel.
- Click the 'Compare' button (or just type — the diff updates automatically).
- Review the color-coded diff: green lines are additions, red lines are deletions, gray lines are unchanged.
- Click 'Clear' to reset both panels and start a new comparison.
FAQ
- Is this tool free?
- Yes, completely free with no usage limits, no sign-up, and no hidden fees.
- Do you upload or store my text?
- No. All comparison happens locally in your browser using JavaScript. Your text never leaves your device.
- Does it work offline?
- Yes. Once the page is loaded, the tool works fully offline — no internet connection required for comparisons.
- What kind of diff algorithm does this use?
- It uses an LCS (Longest Common Subsequence)-based line diff, similar to the classic Unix diff utility, to accurately identify added, deleted, and unchanged lines.
- Can I compare code, not just plain text?
- Yes. The tool compares any plain text, including source code, JSON, markdown, configuration files, or any content you can paste as text.