Diff Checker
Original (A)
Modified (B)
Diff appears as you type
Diff Result

  

Diff Checker Online Free — Compare Two Texts, Files & Code — Free Online Tool

Compare two texts, code blocks or files side by side online free. Line-by-line diff with additions in green and removals in red. Stats, swap A↔B. No upload.

Free Forever
No Signup
No Upload
100% Private
Browser-based

Features

Built for real developer workflows. No fluff, just the tools you need.

Line-by-Line Diff

Every line is compared individually. Additions appear in green (+), removals in red (−). Unchanged lines shown for context.

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Change Statistics

See added lines, removed lines, unchanged lines and percentage changed — updated live as you type.

Swap A and B

Instantly reverse which version is original and which is modified with the Swap button.

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Copy Diff

Copy the full diff output as plain text for commit messages, bug reports or documentation.

Real-time

Diff reruns instantly on every keystroke in either panel. No delay, no clicking.

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Zero Upload

Your text and code never leaves your browser. Safe for comparing private configs and unreleased code.

How to use

Get results in seconds — no account, no file upload required.

1

Paste original text

Paste the original version into the left panel (A).

2

Paste modified text

Paste the new version into the middle panel (B). The diff runs immediately.

3

Review the result

Green lines were added, red lines removed, grey lines unchanged. Copy the diff or screenshot it.

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Frequently asked questions

What types of content can I diff?
Any plain text — code, JSON, YAML, configuration files, Markdown, CSV, SQL queries or regular prose.
Is it character-level or line-level?
Line-level diff — each line is compared as a whole. Character differences within a changed line are not highlighted individually.
Can I compare more than two versions?
This tool compares exactly two versions. For multi-way merges, use a git-based diff tool in your editor.
Is my code safe?
100% safe — your text never leaves the browser. Zero server contact.
Can I load files?
Paste content directly from any file. Click inside a panel and use Ctrl+A, Ctrl+C to copy a file's contents into the clipboard.
Why are many lines showing as changed?
Trailing whitespace or invisible characters can cause lines to appear different. Paste into a text editor and normalize whitespace before comparing.