Text Diff Checker

What is text diff checker?

A diff shows the differences between two versions of a text. Writers use it to review edits, developers use it to compare code and configs and lawyers use it to find changes in contracts.

This tool compares line by line and marks removed lines in red and added lines in green. It runs in your browser, so private drafts and code stay with you.

How to use the text diff checker

1. Paste the original text on the left.
2. Paste the changed text on the right.
3. Press Compare and review the highlighted result.

How the text diff checker works

The tool finds the longest common subsequence of lines between the two texts. Lines that are not part of it are shown as removed from the original or added to the new text.

Worked example

Common uses of the text diff checker

• Reviewing edits made by an editor or teammate.
• Comparing two versions of code or a config file.
• Checking changes in a contract or policy.
• Finding what changed between two exports.
• Verifying that a copy matches the original.

Tips and common mistakes

For a clearer result, keep line breaks consistent in both versions.

Compare small sections at a time. Very long texts are slow to compare in a browser.

Background: what to know before you rely on it

Diff tools trace back to the Unix diff command, created in the early 1970s. The idea is to find the longest sequence of lines that both versions share, then describe everything else as insertions or deletions. Version control systems such as Git use diffs to store history efficiently and to show what changed in each commit. Line based diffs work best for code and structured text. For prose, a word level diff is often more helpful, because a small edit can change a whole paragraph line. When reviewing contracts or important documents, always read the full text as well, since a diff only shows differences and not whether the changes are acceptable.

Private, free and fast

This tool runs entirely in your browser. What you type or choose is not uploaded to a server and is not saved after you close the page, which keeps it fast and private. It is free to use as often as you like. See more in all text tools, or browse the full list of tools.

Related tools

Results are for information and education. For legal, financial, medical or security decisions, check with a qualified professional. Always proofread output before you publish.