viewdiff is a free online diff checker that compares any two texts and highlights every difference instantly. It supports 30+ programming languages with syntax highlighting, auto-formats code with Prettier, and runs 100% client-side — your data never leaves your browser. Use it to compare text, code, JSON, XML, YAML, HTML, CSS, SQL, and more. Side-by-side or inline view, ignore whitespace, share diffs via URL.
How to compare text online
Paste your original text on the left side
Paste the modified text on the right side
See differences highlighted instantly — additions in green, deletions in red
Why developers choose viewdiff
100% private
Your text never leaves your browser. No server uploads, no data collection, no cookies.
Instant — no loading, no friction
Paste and see diffs immediately. No waiting for server processing, no CAPTCHA, no sign-up walls.
30+ languages with syntax highlighting
JavaScript, Python, JSON, YAML, HTML, CSS, Go, Rust, Java, C++, and more.
Auto-format with Prettier
Format messy or minified code before comparing. One click to normalize both sides.
Free forever, no ads
No premium tiers, no feature gates, no ads. Every feature is free with no usage limits.
Features
Compare text, code, and data side-by-side or inline
Syntax highlighting for 30+ languages
Auto-format code with Prettier before comparing
Automatic language detection
Ignore whitespace and case differences
Share diffs via URL — no account needed
Dark and light themes
Keyboard shortcuts and command palette
100% client-side — your data never leaves your browser
No ads, no sign-up, no usage limits
Frequently asked questions
What is a diff checker?
A diff checker is a tool that compares two pieces of text and highlights the differences between them. It shows additions, deletions, and changes line by line — similar to "diff" on the command line, but with a visual interface.
Is this diff checker free?
Yes, completely free with no ads, no sign-up, and no usage limits. viewdiff is free to use for any purpose.
How do I compare two texts online?
Paste the original text on the left and the modified text on the right. Differences are highlighted instantly — no buttons to click.
Is my data sent to a server?
No. viewdiff runs 100% client-side in your browser. Your text is never uploaded, stored, or shared with any server. It is completely private.
What languages are supported?
Over 30 languages including JavaScript, TypeScript, Python, Java, C++, C#, Go, Rust, Ruby, PHP, Swift, Kotlin, JSON, XML, YAML, HTML, CSS, SCSS, SQL, Shell, GraphQL, Markdown, Dockerfile, and more.
Can I compare JSON files?
Yes — viewdiff has a dedicated JSON diff tool that auto-formats your JSON with Prettier and highlights every difference with syntax-aware coloring.
Can I compare code from different programming languages?
Yes. Paste any code and viewdiff auto-detects the language, applies syntax highlighting, and shows differences. You can also manually select a language.
Can I share a diff with someone?
Yes — click the Share button to generate a URL that encodes both texts. Anyone with the link sees the exact same diff. No account required.
What is the difference between side-by-side and inline view?
Side-by-side view shows the original and modified text in two columns. Inline view shows changes in a single column with additions and deletions interleaved — similar to a unified diff.
Can I ignore whitespace differences?
Yes — open Settings and toggle "Ignore whitespace" to hide formatting-only changes and focus on meaningful differences.
How is this different from Diffchecker?
viewdiff is completely free with no ads, runs entirely in your browser (your data stays private), supports 30+ languages with syntax highlighting, and auto-formats code with Prettier. No account needed.
Can I use this as a code comparison tool?
Yes. viewdiff is built for developers — it includes syntax highlighting, auto-formatting, keyboard shortcuts, and a command palette. It works great for reviewing code changes, comparing pull requests, and debugging.