Developer Tools

Diff Checker

Paste two blocks of text and instantly see every addition, deletion, and change highlighted line by line. Perfect for code reviews, config files, and document comparisons. Free, private, runs in your browser.

No uploads — runs in browserFree & no signupLine-by-line diff

Original7 lines

Changed6 lines

How to compare text with Diff Checker

Find every difference between two texts in four steps.

01
Paste your original text
Enter the original version of your text, code, or config file in the left (Original) panel.
02
Paste the changed text
Enter the updated version in the right (Changed) panel.
03
Click Compare
Hit the Compare button to run the diff. The result shows every added line in green and every removed line in red.
04
Copy or download the diff
Use the Copy button to copy the unified diff to your clipboard, or Download to save it as a .txt file.

What people use it for

Six situations where a diff is the fastest way to see what changed.

Code reviews

Quickly spot what changed between two versions of a function, class, or configuration file before merging.

Document editing

Compare two drafts of a document, contract, or article to see exactly what was added, removed, or reworded.

Config file changes

Diff two versions of a JSON, YAML, or .env file to audit changes before deploying to production.

API response comparison

Paste two API responses to find which fields changed, were added, or were removed between versions.

Proofreading

Compare an original text against an edited version to review all changes made by an editor or collaborator.

Database migrations

Compare SQL schema files or migration scripts to verify that only the intended changes were made.

Frequently asked questions

Everything you need to know about the diff checker.

Free, no account, no data stored.

No. The diff algorithm runs entirely in your browser using JavaScript. Your text never leaves your device.

The tool uses a Longest Common Subsequence (LCS) algorithm, the same approach used by Git and most professional diff tools. It produces minimal, accurate diffs.

Yes. Paste any plain text — source code, JSON, YAML, SQL, Markdown, or prose. The tool treats all input as plain text and diffs it line by line.

The left column shows the line number in the original text, and the right column shows the line number in the changed text. Lines that were added or removed only show a number on one side.

Yes. Click Download to save the diff as a .txt file in unified diff format, or Copy to copy it to your clipboard.

Yes. The tool works in any modern browser on desktop or mobile, though a larger screen makes the side-by-side diff easier to read.

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