Dev Tool

Diff Checker

Compare two texts or code files and see exactly what changed. Added, removed and modified lines highlighted instantly.

Original (A)0 lines

Modified (B)0 lines

Original (A)

Modified (B)

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Added lines

Lines present in Modified (B) but not in Original (A) highlighted in green.

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Removed lines

Lines present in Original (A) but removed in Modified (B) highlighted in red.

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Instant comparison

Diffs are computed instantly in your browser — no file upload, no server.

Frequently Asked Questions

What types of content can I compare with the diff checker?

The diff checker works on any plain text — code, configuration files, prose, JSON, XML, CSV, legal documents, or any other text-based content. It performs a line-by-line comparison and highlights added, removed, and changed lines.

Is my text content sent to a server?

No. All comparison processing is done locally in your browser. Neither text input is transmitted to any server, making the tool safe for comparing confidential code, legal documents, or sensitive configuration files.

Can I compare two versions of a file I have saved locally?

Yes. Paste the contents of both file versions into the two input panels and click Compare. The tool does not require file uploads — you just paste text directly, which works for any text file regardless of its extension.

What types of content can I compare?

Any plain text — code files, configuration files, article drafts, CSV data, HTML, JSON, logs or any other text-based content.

Does this work for large files?

Yes. The diff algorithm runs in your browser and can handle thousands of lines. Performance depends on your device but most modern computers handle 10,000+ line comparisons in under a second.

Is my text sent to a server?

No. All comparison happens entirely in your browser using JavaScript. Your text never leaves your device.

What a diff checker shows

A diff compares two pieces of text line by line and marks what was added, removed or changed. Developers use it to review code, but it is just as useful for contracts, terms of service, configuration files, translations or two drafts of an article. The comparison runs in your browser, so the text you paste stays on your device.

Common uses

Contract and policy changes. Compare an old and a new version of terms, a privacy policy or an agreement to see exactly which sentences changed.
Configuration problems. Compare a working config file with a broken one to find the setting that differs.
Code review without Git. Check a snippet someone sent you against your own version.
Content updates. Confirm what an editor or a CMS actually changed on a page.

Getting a clean comparison

Line endings. Windows (CRLF) and Unix (LF) line endings can make every line look changed. Convert both texts to the same style first.
Whitespace. Trailing spaces, and tabs versus spaces, create noise. Trim them if they do not matter.
Structured data. For JSON, format both versions and sort the keys with the JSON formatter, so the diff shows real changes instead of layout.
Re-wrapped paragraphs. Prose that was re-wrapped shows as many changed lines. Put one sentence per line before comparing.

Reading the result

Removed lines are usually marked in red and added lines in green. A line that appears as both removed and added was modified, so look for the small difference: a number, a date or a single word.