How to compare two texts line by line and read the changes

Prepare the two versions as plain text

Use the Text Difference Checker when you have an original and an updated text to compare. Paste the actual text rather than a screenshot or a PDF file. This interface has two text fields; it does not import document files or compare visual formatting. Check that both versions cover the same passage before starting. A missing paragraph in one input will appear as a change, even if it was accidentally omitted while copying. Keep the original versions outside the working fields.

Run a small replacement example

Put A on the first line and B on the second line in Original text. In Updated text, put A on the first line and C on the second. Select Process. The result contains an unchanged A, a removed B and an added C. The summary reports one added and one removed line. There is no separate changed-line total in this interface. A replacement is represented by its removal and addition, so do not count those two rows as two independent wording decisions.

Read additions, removals and unchanged content

The display uses labels and symbols as well as colour: + for added, − for removed and = for unchanged lines. Compare complete rows. A one-letter edit can mark the entire old line as removed and the new line as added; this is not a word- or character-level highlighter. A moved passage may likewise appear as a removal and addition rather than a detected move. The tool compares the supplied strings; it does not judge grammar, meaning, authorship or whether a changed statement is correct.

Check whitespace and line breaks before interpreting

The comparison keeps letter case and spaces significant. A line containing A differs from a line containing A followed by a space. There are no ignore-case, ignore-whitespace or sort-before-comparison options. CRLF and CR line endings are converted to LF before comparison, so that line-ending convention alone does not create different content. An extra blank line can still be an added line. If you deliberately clean the inputs, note what you changed so the comparison still answers the question you intended.

Save the result and respect the input limits

Each input is limited to 20,000 input characters and 500 logical lines; some emoji use more than one unit of that character limit. A visually wrapped paragraph is not several logical lines. Shorten the selection if a limit error appears. Editing either field clears the previous result, so process again after a correction. Copy or download the readable text summary if useful. The download is a text report with line prefixes, not a standard Git patch with file headers and hunk coordinates. The comparison runs locally in your browser without uploading either text.

Sources

• Git: What a patch-format diff contains
• Kervoni: Line comparison implementation