Diffdeck

Open a Git diff in your browser from the terminal.

diffdeck starts a local web UI for the diff you ask Git for, then opens it in your browser. Use it when:

• You do not have a diff view where you are editing.
• git diff in the terminal is too hard to read.
• You are SSHed into a server and still want a clean visual review.

Optionally, you can comment on changed lines and copy all of them at once for your AI to resolve — the surrounding code context goes with them, so the agent has everything it needs to act.

Agentic Setup

Tell your coding agent (Claude Code, Cursor, etc.):

Install `@parthj/diffdeck` globally with `npm install -g @parthj/diffdeck`, then add `alias gd='diffdeck'` to my shell rc file. Run `gd` whenever I ask you to show me a diff.

Install

npm install -g @parthj/diffdeck

The package is scoped, but the installed command is diffdeck.

To update to the latest version:

npm install -g @parthj/diffdeck@latest

(npm update -g won't bump globally-installed packages because they're pinned to an exact version at install time.)

Make It A Drop-In

Diffdeck accepts the same diff arguments, so the simplest setup is a shell alias:

alias gd='diffdeck'

Then use it like git diff:

gd
gd --cached
gd HEAD~1 HEAD

Use It Like Git Diff

diffdeck
diffdeck --cached
diffdeck HEAD~1 HEAD
diffdeck -- -- '*.tsx'

Everything after Diffdeck's own options is passed through to git diff as long as it still produces plain patch output. Summary-only modes such as --stat, --name-only, --raw, and --no-patch are rejected because there is no file patch for the browser to render.

Options

| Option | What it does | | --- | --- | | --repo <path> | Run against another repository. | | --port <number> | Bind to a specific port. Defaults to 4321 (falls back to a free port if taken). | | --host <host> | Bind to a host. Defaults to 127.0.0.1. | | --no-open | Start the server without opening a browser. | | --watch | Watch the selected diff and notify the browser when it changes. | | --watch-interval <ms> | Set the watch polling interval from 100 to 60,000 ms (default 750). | | --editor <command> | Enable “Open in editor” with the configured executable. | | --structural | Enable opt-in Difftastic views when difft is installed. | | --write | Enable confirmed stage, unstage, and revert controls. The default is read-only. | | --debug | Print line-numbered parsing diagnostics. | | --version | Print the installed version and exit. | | --help | Show CLI help. |

Requirements

• Node.js 20 or newer
• Git available on your PATH
• Optional: Difftastic available as difft for structural views

Review workflow

Review state is stored locally in the browser per repository and normalized Git arguments. Viewed files, collapsed files, filters, comment drafts, saved comments, and selection survive reloads. On refresh, unchanged files keep their progress; changed files are reopened and their comments are re-anchored, resolved, or marked stale.

Comments can be copied as a Markdown review packet, downloaded as versioned JSON, or sent to the terminal that launched DiffDeck. Image changes support side-by-side, overlay, and swipe comparison. Supported JavaScript manifests and lockfiles get a package-change summary with a source-diff fallback.

The sidebar is built around the review loop. Its header states which diff you are looking at and how far through it you are. The Files tab lists every change as a tree or a flat list with status, +/−, note counts, and a viewed ring you can tick without leaving your place; / searches it. The Notes tab holds every note grouped by file, and once notes exist the footer offers Copy for agent, JSON download, and Send to terminal. Use the compact review navigator to move between visible files, unviewed files, and changed hunks, or switch to persisted focus mode when one file needs full attention. Review order (path, status, or change size) lives with the filters. Diff settings can rebuild the Git patch while ignoring end-of-line spaces, spacing amount, all whitespace, or blank line changes.

Each file header can create a file-level note, copy its repository-relative path or exact link, and open the configured editor at the selected line. The Notes tab consolidates file and line notes for edit, delete, reopen, and source jumps. Before handoff, expand Preview exact packet to inspect the exact Markdown or versioned JSON that will be copied, downloaded, or sent to the launch terminal.

The accessible linear patch is a first-class review surface with keyboard change navigation, coherent line announcements, comments, and existing note statuses. At narrow widths, Files and Review become two explicit places instead of squeezing the patch.

Keyboard shortcuts

| Key | Action | | --- | --- | | j / k | Next / previous visible file | | Shift+j / Shift+k | Next / previous unviewed file | | n / p | Next / previous changed hunk | | f | Toggle focus mode for the selected file | | a | Toggle the accessible linear patch for the selected file | | v | Toggle viewed for the selected file | | c | Start a comment at the first changed line | | x | Collapse or expand the selected file | | / | Search files in the sidebar | | s | Open diff settings | | o | Open the selected file in the configured editor | | ? or Cmd/Ctrl+K | Open the command palette and shortcut reference | | Cmd/Ctrl+Enter | Submit the comment, note, or edit you are typing | | Esc | Leave a comment box with the draft intact, or close the open panel |

Typing always wins. While focus is in any text field — a comment box, the path filter, the file search, the command palette, or a native select — every key is text and no single-key shortcut fires. Open dialogs, popovers, and menus own the keyboard until they close (Esc). Holding a key steps through files and hunks but never flips a toggle back and forth, and IME composition keystrokes are never shortcuts. Each comment box shows how to hand the keyboard back: Cmd/Ctrl+Enter to finish, Esc to leave.

Security and repository writes

DiffDeck binds to loopback by default. When --host exposes it beyond loopback, the CLI generates a random capability token, prints and opens the complete tokenized URL, and requires that token for every API, event, image, editor, structural, terminal, and write request. Treat that URL as a secret: anyone who has it can read the selected diff while the process is running.

Repository mutation controls do not exist unless DiffDeck starts with --write. Every action is restricted to a path in the current snapshot; stale snapshots are rejected. Revert actions require confirmation, and file or individual-hunk scope is shown before the action runs.

Develop

bun install
bun run dev
bun run check

Releases

See GitHub Releases for the full version history. Highlights:

• Next release — Review navigator/focus mode, safe deep links and file notes, Git-owned whitespace modes, tree/flat ordering, review notes and exact packet preview, accessible patch, responsive redesign, and exhaustive release hardening. See release notes and verification evidence.
• 0.3.8 — Refined the review UI with shared controls, icons, compact states, and better mobile diff layout.
• 0.3.7 — Browser page refreshes now reload the current git status instead of reusing a cached session.
• 0.2.0 — File-list virtualization for large diffs (23k+ files), survives non-ASCII patches, comment drafts persist across scroll.
• 0.1.3 — Float copy-comments FAB, render binary file placeholders, oklch theme tokens.
• 0.1.1 — Initial scoped npm release.

License

MIT

Author

Created by Parth Jadhav.