Code diff
Compare two versions of a file in any programming language to spot edited lines before a commit, review a refactor, or find the change that broke something.
Diff Checker - Compare Text Online
Paste or upload two versions of a text and see every added, removed and changed line in seconds - without your data ever leaving your browser.
Original text
Changed text
100% private
The comparison runs entirely in your browser. Your text is not uploaded or logged; one restore session may be kept locally on your device.
Fast diff engine
An optimized Myers algorithm highlights line, word and character changes in milliseconds.
Free, no sign-up
Unlimited comparisons for text, code and config files. No account, no installation.
How to compare two texts
Paste or upload both versions
Put the original text in the left editor and the changed text in the right editor. You can paste from the clipboard or upload plain-text files.
Click Compare
The diff is computed instantly on your device. Choose smart, word or character precision for the inline highlights.
Review and copy the result
Removed lines are marked red, added lines green, and changed lines show exactly what was edited. Switch between split and unified views, or hide unchanged lines.
Your text never leaves your browser
Many online comparison tools send your content to a server to compute the diff. This tool does not: the comparison runs locally in your browser using JavaScript, so your text is not transmitted to our servers or shared.
That makes it suitable for sensitive content such as contracts, source code, configuration files and personal documents. To recover from accidental reloads, one recent session can be stored locally in your browser and cleared from the tool or browser settings.
What can you compare?
Anything that is plain text can be diffed - here are the most common uses:
Documents and essays
Check two drafts of an article, essay or contract for edits, and verify that nothing important was added or removed between versions.
Configs, JSON and logs
Diff environment files, JSON or YAML configuration and log output to track down what changed between two deployments or runs.
Supported text formats
The tool compares any plain-text content. Upload or paste files such as:
.txt, .md, .csv, .json, .xml, .yml, .html, .css, .js, .ts, .jsx, .tsx, .py, .r, .java, .c, .cpp, .go, .rs, .rb, .php, .sql, .sh, .ini, .env, .log
Binary formats such as PDF, Word documents or images are not supported in this version.
Frequently asked questions
Is my text uploaded to a server?
No. The comparison runs entirely in your browser. You can verify this in your browser's developer tools: no network requests are made when you click Compare.
How do I compare two text files?
Paste both versions into the editors, or use the upload buttons to load plain-text files from your device, then click Compare. Differences are highlighted immediately.
Can I compare source code?
Yes. The diff works line by line and highlights inline changes, which makes it well suited for code in any language, as well as JSON, YAML and other configs.
What do the colors mean?
Red marks lines or characters that were removed from the original text, and green marks content that was added in the changed text. A line shown in both colors was modified.
Is there a size limit?
There is no hard limit, but very large inputs (several megabytes) can be slow because the comparison runs on your device. The tool warns you when input is large.
Is this diff checker free?
Yes. Comparing text is free and unlimited - no account, subscription or installation required.