DevToolbox

Text Diff Checker

Comparing two versions of text by eye is slow and error-prone, especially with long documents or code. This diff tool compares an "Original" and a "Modified" text side by side and highlights exactly what was added, removed, or changed, line by line.

Enter text in both boxes and click "Compare."

Your data stays in your browser — this tool runs entirely on the client side and nothing is uploaded to a server.

How to Use the Text Diff Checker

  1. Paste the original text into the left box.
  2. Paste the modified text into the right box.
  3. Click "Compare" to see additions highlighted in green and removals highlighted in red.

What a text diff shows you

A diff compares two pieces of text line by line and identifies which lines are unchanged, which were added, and which were removed. This makes it easy to spot exactly what changed between two versions without manually reading through both from top to bottom.

Common uses for diffing

Developers use diffs constantly during code review to see exactly what a change modifies. Diffs are also useful for comparing two versions of a configuration file to spot an unintended change, comparing two drafts of documentation or a legal document, or checking whether an automated process produced the output you expected.

Example

Simple change
Original: Hello world
Modified: Hello there world
Added: "there"

Tips

  • This is a line-based diff — for very long single lines, consider breaking text into multiple lines first for clearer results.
  • Whitespace-only differences can be easy to miss visually — the diff will still flag them as changes.

Frequently Asked Questions

Does this compare files or just pasted text?

It compares pasted or typed text directly. You can copy the contents of a file into either box to compare file contents.

Is my text uploaded anywhere?

No, the comparison runs entirely in your browser using JavaScript.

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