Text Diff Comparison Tool

Compare two blocks of text side-by-side and highlight differences instantly.

How to Use Text Diff Comparison Tool

1

Paste original text

Enter the first version of your text in the left panel.
2

Paste modified text

Enter the second version of the text in the right panel.
3

View the differences

See additions, deletions, and changes highlighted in color.

Tested tool guide Text and writing tools Checked August 16, 2026

What Text Diff Comparison Tool does, with a checked example

Paste two versions of a document, code snippet, or any text into the two panes and the tool marks every added, removed, and changed line or character. It works entirely in your browser, so nothing leaves your machine. The most common surprise is that whitespace counts: a trailing space or a changed indentation registers as a difference. If you want to ignore formatting, you must normalize the text yourself before comparing, because the tool compares what you paste verbatim.

Worked example

A concrete input and expected output from the current implementation.

Input

[object Object]

Expected output

In the side-by-side view, the first line appears unmarked in both panes. The second line is highlighted as a change: 'jumps over the lazy dog.' on the left, 'jumps over the lazy cat.' on the right.

The first line matches exactly, so the tool shows it unmarked. The second line differs at the final word, so the tool marks it as a change in both panes.

How the result is produced

Line-by-line alignment

The tool splits each input into lines and aligns them so that corresponding lines are shown side by side. It then marks lines that appear in only one side as insertions or deletions, and lines that match with minor changes as substitutions. The result is a side-by-side view with added and removed lines highlighted in distinct colors, so you can scan the differences at a glance.

Displaying changed lines

When a line differs between the two inputs, the tool flags it as a change and shows both versions side by side: the original line in the left pane and the revised line in the right pane, each highlighted. A changed line appears in both panes, so it is easy to tell apart from an added or removed line, which appears in only one pane.

Good uses

Reviewing a colleague's edits to a document or email draft before you accept or reject them.
Checking whether a minor change you made to a configuration file accidentally altered something else.
Verifying that two versions of a product description or legal clause are identical except for the intended wording.

Limits and checks

Whitespace is significant: a trailing space, extra blank line, or changed indentation is reported as a difference even when the visible text is unchanged.
Reordered blocks may appear as a deletion and an insertion rather than a move, because the tool matches content positionally, not semantically.
Very long inputs may make the comparison slow; the tool has no length limit stated, but performance degrades as the number of differing lines grows.

Common questions

Does the tool ignore trailing spaces or line endings?

No. It compares the raw text you paste, including spaces, tabs, and line breaks. If you want to ignore such differences, you must clean the text yourself before pasting, for example by converting CRLF to LF or trimming trailing spaces.

Can I compare two files by uploading them?

The tool accepts pasted text in two input areas. It does not offer file upload in the described workflow. You would need to open each file, copy its contents, and paste them into the corresponding pane.

References and verification

The example and behavioral notes were checked against the browser implementation. Standards and primary references below define the relevant format, formula, or platform behavior.