Text Diff Checker
Open toolCompare two blocks of text and see line-by-line differences highlighted.
Paste two versions of some text and see exactly which lines were removed and which were added. Good for comparing config files, drafts, code snippets, or two copies of a list.
How it works
Both texts are split into lines, and the tool finds the longest run of lines the two versions have in common (a longest-common-subsequence comparison — the same idea behind diff). Everything in the Original that is not part of that shared run is shown as removed, and everything in the Changed text that is not part of it is shown as added.
Lines are compared as whole lines and must match exactly, including capitalisation, spacing at the start or end of the line, and punctuation. Nothing is compared inside a line.
How to use it
- Paste the older text into Original.
- Paste the newer text into Changed.
- Read the Differences panel: red lines starting with
-were removed, green lines starting with+were added, and plain lines are unchanged. - Click Download to save the comparison as a text file.
Options & controls
Inputs
- Original
- The starting version — what you are comparing from.
- Changed
- The new version — what you are comparing to.
Phone layout
- Original / Changed / Differences switcher
- Below the
smbreakpoint (phones), the two inputs and the result would fill three screens, so a three-way switch shows one at a time. On wider screens it is hidden: the two inputs sit side by side with the differences below.
Actions
- Download
- Saves the differences as
diff-report.txt, using the same prefixes as the screen: two spaces for unchanged,-for removed,+for added. Only shown when there is at least one difference. - Reset
- In the title row. Clears both texts.
Reading the results
Differences panel
- Red line starting with -
- This line is in Original but not in Changed.
- Green line starting with +
- This line is in Changed but not in Original.
- Plain line (indented two spaces)
- This line is the same in both versions. It is shown for context, in its position.
- No differences found
- The two texts are identical, line for line. It is also what you see while both boxes are empty.
Tips & guidelines
- A changed line is shown as one removed line followed by one added line — there is no in-line highlighting of which words changed. Compare the pair by eye.
- If you see everything marked as changed, check for differences you cannot see: trailing spaces, tabs versus spaces, or different line endings.
- For a prose comparison, put each sentence on its own line first so the diff points at sentences rather than whole paragraphs.
Limits
- Line-by-line only: there are no options to ignore whitespace, ignore case, or compare by word or character.
- An empty box counts as one blank line, so comparing empty text against real text may show a single removed blank line above the added lines.
- Very large inputs (many thousands of lines on each side) can make the page slow, since the comparison grows with the product of the two line counts.
Saved in your browser
Nothing. Both texts exist only on the page.