— Text & writing

Text Diff Checker

Paste two versions of any text and see exactly what was added and removed, line by line, all in your browser.

— What it does

The Text Diff Checker is a free tool that compares two blocks of text and highlights the differences line by line. It uses a longest-common-subsequence algorithm to show added lines, removed lines, and unchanged context, plus a count of how many lines changed — so you can spot edits in code, config, copy, or any plain text in seconds.

  • Line-based diff powered by an LCS algorithm for accurate, minimal change sets.
  • Unified view marking added (+) and removed (−) lines with surrounding context.
  • Live counts of added and removed lines as you type.
  • Runs entirely in your browser — your text is never uploaded to a server.

How to use it

1

Paste the original text

Put the first or older version of your text in the left input box.

2

Paste the changed text

Put the second or newer version in the right input box to compare against.

3

Read the diff

The unified diff updates instantly, marking added lines with + and removed lines with −, along with the change counts.

Frequently asked

Is my text uploaded anywhere?
No. The comparison runs entirely in your browser with JavaScript. Nothing you paste is sent to a server or stored, so it is safe for confidential documents and code.
How does the diff decide what changed?
It splits both inputs into lines and runs a longest-common-subsequence (LCS) algorithm to find the smallest set of additions and deletions that turns the original into the changed version.
Does it compare word by word or character by character?
This tool compares line by line, which is ideal for code, config files, and prose. A line that changed shows up as one removed line and one added line.
Can it handle large files?
It handles typical documents and source files comfortably. Very large inputs (tens of thousands of lines) are capped gracefully with a notice so the page stays responsive.

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— Built by saavos

These tools are free. So is the first version of your agent.

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