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Text Compare and Diff Checker

Paste two versions of a text and see exactly which lines were added, removed or left alone.

Runs in your browser. Nothing you type is sent to a server.

How to use Text Diff Checker — Compare Two Texts Online Free

  1. 1Paste the original text on the left and the changed version on the right.
  2. 2Turn on Ignore case or Ignore whitespace to filter out formatting noise.
  3. 3Added lines are highlighted green and removed lines red, side by side with line numbers.

About Text Diff Checker

Spotting the difference between two nearly identical documents by eye is a reliable way to miss something. A diff does it mechanically: align the parts that match, highlight everything that does not.

The alignment is what separates a useful diff from a useless one. Comparing line 1 with line 1, line 2 with line 2 breaks completely the moment a line is inserted near the top — everything after it reads as changed. This tool computes the longest common subsequence instead, so an insertion shows up as one added line and the rest stays aligned, the same way Git behaves.

The ignore options exist because formatting changes drown out real ones. Reindenting a file or changing line endings can make every single line look modified; switching whitespace off leaves only the differences that actually matter.

Frequently asked questions

How does it decide what changed?
It finds the longest common subsequence of lines between the two versions, so unchanged blocks stay aligned even when large sections are inserted or deleted. That is the same approach Git's diff uses.
Can it compare code?
Yes. Any plain text works — code, configuration, CSV, logs or prose. Indentation is preserved, and you can ignore whitespace if reformatting is creating noise.
What do the ignore options do?
Ignore case treats Hello and hello as identical; ignore whitespace collapses runs of spaces and trims line ends. Both affect only the comparison — the text shown is always your original.
Is there a size limit?
Very large documents fall back to a simpler line-for-line comparison so the page never freezes. For anything up to a couple of thousand lines each you get the full alignment.
Are my documents uploaded?
No. Both sides are compared in your browser, which matters when diffing a contract, a config file or anything else you would not paste into a stranger's server.
Is it free?
Yes — unlimited use, no sign-up, no watermark and no limit on how many times you run it.