Diff Bro

An offline-only desktop diff viewer / sharing app for Windows and macOS — GitHub-style rendering, serious about privacy. Electron + Vue 3 + Pinia + Monaco.

It never makes a network request: files stay on your machine, enforced by a session-level kill-switch, a strict CSP, and a sandboxed renderer. See docs/security.md.

Download

Grab the latest installer for your OS — no account, no telemetry, no auto-update:

OS	Download
Windows (10/11)	Diff-Bro-Setup-Windows.exe
macOS	Diff-Bro-macOS.dmg

Or browse all releases.

macOS via Homebrew (updates with brew upgrade):

brew tap mindaugaskasp/tap
brew install --cask --no-quarantine diff-bro

--no-quarantine skips the Gatekeeper prompt described below (the build isn't notarized yet). The cask is refreshed automatically on every release.

Builds are unsigned for now (no Apple/Microsoft cert yet):

• Windows — SmartScreen warns; click More info → Run anyway.

• macOS — Gatekeeper says "Diff Bro is damaged and can't be opened." It isn't damaged — that's just how recent macOS reports an unsigned, un-notarized app that was quarantined on download. Drag it to Applications, then run once in Terminal:

  xattr -dr com.apple.quarantine "/Applications/Diff Bro.app"

  and open it normally. More detail in docs/packaging.md.

Features

• Diff two files or pasted text — split/inline, word-level highlights, syntax highlighting, live re-diff when a file changes on disk, and an in-view search (plain / regex, match count, jump-to-match).
• Drag & drop files onto the window (two at once builds the diff; a third starts over). Fixed, single window; light/dark themes; clamped zoom.
• Saved diffs — AES-256-GCM encrypted at rest, auto-expiring (≤ 24 h), organized into categories, favoritable.
• Share a saved diff as a sealed, signed .diffbro file for one recipient; manage named trusted keys under the Security menu.
• Snippets — an encrypted, categorized, non-expiring text library with per-snippet syntax (JSON / SQL / Markdown / YAML / Python / Bash / PHP / …), filter + copy, and passphrase-protected export/import.
• Tools — Base64, and JSON / XML / SQL format+validate (Monaco-highlighted, with "Add to Snippets"), plus a passphrase text Encrypt/Decrypt.
• Config backup/restore — one passphrase-encrypted file for your keys, trusted hosts, snippets and settings (not diffs).

JSON/XML content shows an inline "pretty-print it?" banner before you diff.

Screenshots

Light and dark themes, GitHub-style rendering.

Saved diffs are encrypted on-device and auto-expire.

Quick start

npm install
npm run dev
npm run check   # ESLint + Vitest — run before every change lands

No local Node? The same flow runs in Docker: make dev (app via noVNC at http://localhost:6080/vnc.html) and make check. See docker/README.md and make help.

Docs

• Architecture — processes, trust boundary, directory map.
• Security model — offline guarantee, sharing, keys, backup.
• Packaging & releasing — installers, signing notes, CI.
• Coding standards and hard rules live in CLAUDE.md; roadmap in DEVELOPMENT_PLAN.md.