Compare Code Online
Paste two code snippets and instantly see the differences highlighted line by line and word by word. Supports JavaScript, Python, CSS, HTML, SQL, JSON, and more.
Paste code in both panels above to see the diff
Differences are highlighted directly in the panels as you type
Inline Highlights
Changed words are highlighted directly inside the code panels — red for removed, green for added — so you see changes in full context.
Multi-Language
Works with JavaScript, TypeScript, Python, CSS, HTML, SQL, PHP, Java, JSON, and any plain-text code or config file.
100% Private
All diffing happens locally in your browser. Your code never leaves your device — no server, no upload, no tracking.
Where to Use This Tool
Any time you need to spot the exact difference between two versions of code.
Code Review
Before submitting a PR or reviewing someone else's changes, paste both versions to get a clear color-coded diff without leaving your browser.
Debugging
Compare a working version of a function with the broken one to instantly spot the line or variable that changed.
Config & Env Files
Compare .env files, JSON configs, YAML, or Dockerfiles between environments (dev, staging, prod) to catch missing or changed settings.
Version Tracking
Compare snippets copied from Git history or documentation to understand exactly what changed between two releases.
Learning & Teaching
Show students the before and after of a refactoring session, or compare your solution to a reference implementation.
API & Schema Diffs
Paste two versions of a JSON schema, GraphQL schema, or OpenAPI spec to find added, removed, or renamed fields.
Frequently Asked Questions
Q.Is my code safe?
Yes. All comparison happens entirely in your browser. Your code is never sent to any server — it's 100% private and secure.
Q.What languages are supported?
The diff engine works on any text-based language — JavaScript, TypeScript, Python, CSS, HTML, SQL, PHP, Java, JSON, YAML, and more. The language selector adjusts labels and placeholders.
Q.What does 'Ignore Whitespace' do?
When on (default for code), differences caused only by leading/trailing spaces or tabs are ignored. Useful when comparing re-indented code.
Q.What does 'Ignore Case' do?
Uppercase and lowercase letters are treated as identical. Useful when casing conventions changed, e.g. camelCase vs PascalCase.
Q.How does the diff panel work?
Below the editors you'll see a unified diff with old/new line numbers, a +/− prefix, and word-level highlights showing exactly which characters changed.
Q.Can I compare large files?
Yes. The diff runs entirely in your browser with no upload limit. Very large files may take a brief moment, but there is no hard size restriction.