Press Ctrl or Cmd+Enter to compare.
Compare two texts with this diff checker
A diff checker shows exactly where two versions of text stop matching. Paste the older version on the left and the newer version on the right. The result keeps matching lines together and marks replacements, additions and removals with their line numbers. This is useful for source code, configuration, drafts, lists and any other plain text.
Red marks text that existed only in the original. Green marks text that appears only in the changed version. When a removed line and an added line are next to the same matching lines, they are displayed together as a replacement. The counters separate replacements from lines that were only added or removed.
Comparison runs in your browser. QwHub does not upload or store either text. The checker compares characters and lines; it does not decide whether two sentences have the same meaning.
How the line-by-line comparison works
The checker looks for lines that both versions have in common, then aligns the unmatched sections between them. “Ignore whitespace” treats repeated spaces, tabs and spaces at the ends of lines as equal. “Ignore letter case” treats pairs such as Name and name as equal, while the displayed text remains unchanged.
For unusually large inputs, the tool protects the browser from an expensive full comparison. It still matches the common beginning and end, then shows the unmatched middle as one changed block.
| Color | What it means |
|---|---|
| Red | A line was removed from the original or replaced. |
| Green | A line was added to the changed text or is the replacement. |
| White | The line matches under the selected options. |
How to compare two texts
- Paste both versions: Put the original text on the left and the changed text on the right.
- Choose what matters: Ignore whitespace or letter case only when those changes are not important.
- Review the diff: Press Compare and use the colors, line numbers and counters to inspect the changes.
Frequently asked questions
Are the texts uploaded or saved?
No. The comparison happens in this browser tab. QwHub does not receive or store the text you paste.
What does “Ignore whitespace changes” do?
It treats leading and trailing spaces, repeated spaces and tabs as equivalent. Line breaks still define separate lines.
Can I compare Word, PDF or binary files?
This tool compares plain text. Copy the text from a document first; it does not read formatting, tracked changes, images or binary file data.
Why can changed lines appear as removed and added?
The checker aligns exact lines that both versions share. If there is no nearby shared line, an unmatched block may be shown as separate removals and additions rather than a one-for-one replacement.