Text Diff Checker

Compare two blocks of plain text

Paste the original and revised text to see which lines differ. Results update as you type, and you can switch the editor layout, ignore case or horizontal whitespace, show line numbers, swap inputs, and copy the result. Text is compared locally in the browser.

A reproducible example

Original:

name: Alice
status: draft
count: 2

Revised:

name: Alice
status: ready
count: 3

The result has two modified lines, no separately added lines, and no separately deleted lines. Copying produces this readable comparison:

  name: Alice
- status: draft
+ status: ready
- count: 2
+ count: 3

You can fill this example using the example button. Replacing a line increments the modification counter once, even though the output shows one removed version and one added version.

Steps and display options

1. Paste the earlier text into Original and the newer text into Modified.
2. Review the difference count and highlighted lines; no separate compare action is required.
3. Choose split or unified layout. These change the editor arrangement, not the comparison algorithm.
4. Turn line numbers on when you need to refer to positions, then copy the result or clear both inputs.

Added lines use a plus prefix and removed lines a minus prefix. Unchanged lines remain in the output for context. Blank lines are meaningful; adding a final newline can add an empty line to the comparison.

Ignoring case or whitespace

Ignore case compares Alice and ALICE as equivalent, while retaining the original capitalization in the displayed unchanged line. It does not rewrite your input into lowercase.

Ignore whitespace removes spaces and Tab characters for each line's comparison. Line breaks remain separate, so two lines do not silently collapse into one. Original spacing is preserved in the output. Leave this option off when spacing itself matters, such as indentation-sensitive code or fixed-width records. CRLF and LF line endings are normalized before comparison.

What the algorithm can and cannot do

This is a positional line-by-line comparison: line 1 is checked against line 1, then line 2 against line 2. It does not use Myers or longest-common-subsequence matching, and it does not highlight individual changed characters or words within a line.

For example, comparing A\nB with A\nX\nB reports a replacement at line 2 and an addition at line 3. It does not realign the old B with the new B automatically. A middle insertion may therefore make later lines appear changed. Use an alignment-aware diff tool for reviewing complex code revisions or generating patches.

Copying and practical limits

The copied text uses plus/minus prefixes for reading and sharing. It lacks file headers and hunk coordinates, so it is not an apply-ready Git patch. There is no HTML/PDF export, syntax-aware comparison, or built-in file uploader.

There is no measured universal accuracy percentage or guaranteed response time. Very large inputs are processed on the browser thread and may slow editing. Compare focused sections when necessary, and keep your original source files for verification.

Related workflows

Use the JSON formatter to make two API responses easier to compare. Use the CSV viewer when you need columns, filtering, and a table view rather than a plain-text comparison.