Up to 200,000 characters and 2,000 lines per pane. Very large line-pair comparisons are stopped before they can freeze the page.
Paste one or two versions, choose the comparison rules, then select Compare texts.
Your original and modified text stay on your device. Comparison, copying, and diff download run in your browser; only one anonymous tool-use total is sent after a successful comparison.
How to Use the Text Difference Checker
- Paste the earlier version into Original text.
- Paste the newer version into Modified text.
- Choose whether case, whitespace changes, or blank lines should be ignored.
- Select Compare texts, then switch between the side-by-side and unified views.
- Copy the summary and unified diff, or download the .diff file for your own records.
How Line and Word Differences Are Matched
The first pass normalizes Windows and classic Mac line endings, applies only the ignore rules you selected, and finds a longest common subsequence of lines. This preserves unchanged lines when a paragraph is inserted or removed instead of treating every later line as different.
Inside each change block, one removed line is paired with one added line in order. A second longest-common-subsequence pass over words, whitespace, and punctuation highlights the smaller edits inside that pair. A changed-line pairing is a review aid, not a claim that the two lines have the same meaning.
Text Comparison Examples
One word changes in a sentence
Comparing “Status: draft” with “Status: ready” produces one changed line. The side-by-side view keeps “Status:” unmarked and highlights only the removed and added words.
A line is inserted
When the modified version adds a new bullet between unchanged bullets, the line pass marks one added line and keeps the surrounding lines aligned.
Formatting-only revisions
Ignore whitespace changes collapses spaces and tabs within each line while retaining line boundaries. Ignore blank lines removes whitespace-only lines from matching. Ignore case treats uppercase and lowercase forms as equal.
Limits, Unified Output, and Privacy
The unified download contains the complete compared view in a familiar minus, plus, and context format. Ignore rules intentionally omit ignored differences, so disable them when the output must preserve every formatting change. This browser tool does not detect moved blocks, understand prose meaning, merge edits, compare rich-text formatting, or promise compatibility with every patch program.
The pasted text is never placed in a URL or sent to the content API. The character, line, and line-pair limits stop unusually expensive comparisons before they can lock the browser. For a repository-sized or binary comparison, use a dedicated version-control or desktop diff tool instead.