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Text Difference Checker
Compare an original and a changed version of any text and see what was added, removed, and kept — word by word or line by line.
Checking tool availability…
Text Difference Checker works on your text locally in your browser.
See exactly what changed between two versions
Edits are easy to miss when you read two versions side by side: a changed date, a dropped word, a line removed from a list. Paste the original and the changed text — or upload two documents — and every difference is marked in one view, with removed text struck through and added text underlined. Use word comparison for edited writing, and line comparison for lists, logs, and configuration files.
How to compare two texts
- Paste the earlier version into Original text and the newer version into Changed text, or use Upload Original and Upload Changed.
- Choose Word comparison or Line comparison. The differences update as you type, with counts of what was added, removed, and unchanged.
- Use Swap Texts to compare in the other direction, and Copy Differences to take a plain-text copy of the result.
How the comparison works
- The checker finds the most text the two versions have in common, in the same order, and marks everything else as removed from the original or added in the changed version.
- Word comparison looks inside each changed line, so a single edited word is highlighted instead of the whole line.
- Line comparison treats each line as one unit — a line with any change shows as one removed line and one added line.
- Windows and Mac/Linux line breaks count as the same, and a final line break is ignored; spaces and blank lines inside the text do count.
- Nothing is judged as a “move” — text that moved shows as removed in one place and added in another.
| Original | Changed | Mode | Copied differences |
|---|---|---|---|
| The meeting is on Tuesday at 3 pm. | The meeting is on Thursday at 4 pm. | Word | The meeting is on [-Tuesday-]{+Thursday+} at [-3-]{+4+} pm. |
| Please send the final report. | Please send the report by Friday. | Word | Please send the[- final-] report{+ by Friday+}. |
| apples bananas cherries | apples blueberries cherries dates | Line | apples - bananas + blueberries cherries + dates |
Your text stays on your device
- Both texts are compared by JavaScript running in your browser.
- Your text is never uploaded to Looty Tools or any other server.
- Uploaded documents are opened and read in your browser; the files themselves are never sent to Looty Tools.
- Nothing is stored — refreshing or closing the page clears both boxes.
Limitations
- Each box can hold up to 100,000 characters for comparison. Longer texts are not compared; split them into parts.
- If two large texts are almost completely different, the checker stops matching after a fixed amount of work so the page stays responsive, and shows the unmatched part as removed and added text.
- Languages written without spaces, such as Chinese and Japanese, are compared in whole runs of characters rather than individual words.
- Uploads accept .txt and .md files up to 5 MB, Word .docx files up to 15 MB, and PDFs up to 25 MB and 50 pages. Only the text is compared — formatting and images are not.
- There are no options to ignore case or spacing; every character counts.
Related text tools
- Remove Duplicate LinesDelete repeated lines and keep one copy of each.
- Sort Lines AlphabeticallySort each line from A to Z.
- Find and Replace TextReplace one phrase with another across the whole text.
Guides
- How Text Comparison WorksThe idea behind diff tools: the longest common subsequence, the Myers algorithm, line versus word pieces, and what a text comparison cannot show.
- Word Diff vs. Line DiffWhen to compare text word by word and when line by line, with examples of how the same edit looks in each view and what trips each one up.
- Compare Drafts, Lists, ConfigsPractical workflows for comparing document drafts and contracts, finding changes between two lists, and spotting differences in settings files.
Text Difference Checker FAQ
- What is the difference between word and line comparison?
- Word comparison marks the exact words that changed inside sentences, which suits edited drafts. Line comparison treats each line as a unit and marks whole lines as added or removed, which suits lists, logs, and configuration files.
- How are changes marked?
- Removed text is struck through and added text is underlined, each on a colored background, and screen readers announce them as removed and added. Line comparison also shows a − or + before each changed line.
- Do line endings or a final line break count as changes?
- No. Windows and Mac/Linux line breaks are treated the same, and a line break at the very end of either text is ignored. Spaces and blank lines inside the text do count.
- How much text can I compare?
- Up to 100,000 characters in each box. If two very large texts are almost completely different, the checker stops matching them up after a fixed amount of work and shows the unmatched part as removed and added, so the page never freezes.
- Can I copy the result?
- Yes. Copy Differences copies a plain-text version: in line comparison, added lines start with “+ ” and removed lines with “- ”; in word comparison, changes are written as [-removed-] and {+added+}.
- Can I compare Word documents or PDFs?
- Yes. Upload Original and Upload Changed each read a .txt, .md, Word .docx, or text-based .pdf file in your browser. Only the text is compared, not formatting, and scanned PDFs without a text layer are not supported.
- Is my text uploaded?
- No. Both texts are compared in your browser and never sent to Looty Tools or saved.
