About Online Diff
A free, fast, privacy-first diff tool that runs entirely in your browser.
What it does
Online Diff lets you compare two pieces of text, code, or structured data and see exactly what changed. Differences are highlighted line by line, with character-level or word-level inline highlighting for changed lines. It supports side-by-side and unified diff views, syntax highlighting for 13 programming languages, and structured comparison modes for JSON, CSV, YAML, and XML.
You can paste text directly, drag and drop files, or share any diff via a URL. Share links encode the full diff content in the URL itself — no server involved. An optional password-encryption feature lets you share sensitive diffs securely.
Why we built it
Privacy by default
Most online diff tools send your content to a server. That's a problem when you're comparing API responses with tokens, internal configs, or production data. Online Diff never transmits anything — the diff algorithm runs locally in your browser tab.
Instant results
Because there's no round-trip to a server, diffs are computed the moment you stop typing. No loading spinners, no waiting for an API call to return.
Structured format support
Raw text diffs are useful, but a JSON or CSV diff is much more readable when displayed in its native structure. Online Diff automatically detects JSON and CSV input and offers a structured view alongside the standard text diff.
No account needed
No signup, no login, no email address. Paste, compare, done. Share links work without the recipient creating an account.
What you can compare
- Text files — documentation, changelogs, log files, configuration files, environment variables
- Source code — JavaScript, TypeScript, Python, Go, Rust, Java, SQL, Shell scripts, and more with syntax highlighting
- JSON — API responses, feature flag configs, package.json, structured data exports; structured key-by-key comparison
- CSV — data exports, reports, migration outputs; row and cell-level comparison in a table view
- YAML — Kubernetes manifests, Docker Compose, GitHub Actions, Helm charts, Ansible playbooks
- XML — configuration files, SOAP responses, data feeds, SVG files
How it is built
Online Diff is built with Next.js (App Router) and hosted on Netlify. The diff engine uses the jsdiff library, which implements the Myers diff algorithm — the same algorithm used by Git. Syntax highlighting is provided by Shiki, which runs server-side so there is no client-side JavaScript overhead for highlighting. The UI is built with Tailwind CSS and shadcn/ui.
Encryption for password-protected share links uses the browser's native Web Crypto API (AES-GCM with PBKDF2 key derivation) — no third-party library, no server key management.
Get in touch
Found a bug or have a feature request? Open an issue on GitHub. Pull requests are welcome.