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ToolzKit

Text

Text Diff Checker

Compare two texts line by line and highlight additions, removals and unchanged lines.

Original

Changed

Added lines
0
Removed lines
0
Unchanged lines
1

Diff

Paste original and changed text above to compare.

About the Text Diff Checker

Text Diff Checker compares two blocks of text line by line using a longest common subsequence algorithm, the same approach behind most version control diff tools. It clearly marks which lines were added, removed or left unchanged, making it easy to review edits between two drafts, configuration files or code snippets.

How to use it

  1. 01Paste the original text into the left panel.
  2. 02Paste the changed text into the right panel.
  3. 03Review the colour-coded diff output below, with additions and removals marked.
  4. 04Toggle ignore-whitespace or ignore-case if formatting differences aren't meaningful to your comparison.

Features

  • Real longest common subsequence (LCS) line-level diff algorithm
  • Colour-coded output: additions, removals and unchanged lines
  • Ignore-whitespace and ignore-case comparison options
  • Summary counts of added, removed and unchanged lines

Practical examples

Reviewing edits

Compare an original paragraph against an edited version to see exactly which sentences changed.

Config file comparison

Paste two versions of a config file to spot which lines were added or removed between deployments.

Limitations

  • Comparison is line-based, not word- or character-based, so a single word change marks the whole line as different.
  • Very large inputs may take longer to process since LCS diffing has quadratic time complexity in the number of lines.

Privacy

Both text inputs are compared entirely in your browser and are never uploaded or transmitted.

Read the full privacy policy for how the site as a whole handles data.

Frequently asked questions

Why does a line show as both removed and added?

When a line changes slightly, the algorithm often reports the old version as removed and the new version as added, since it compares whole lines.

Can I compare code files?

Yes, any plain text works, including code, configuration files and structured data.

Does it support word-level highlighting?

No, this tool performs line-level diffing only; word-level differences within a changed line are not individually highlighted.