Installation

nittle ships as a single self-contained binary. It embeds its own web client and needs no checkout, no Node, and no sidecar files. The only prerequisite is git on your PATH.

Install

macOS / Linux

curl -fsSL https://nittle.dev/install | sh

Windows

irm https://nittle.dev/install.ps1 | iex

The installer downloads the binary for your OS and architecture, verifies its SHA-256 against the published checksum manifest, and installs it to ~/.nittle/bin. It adds that directory to your PATH for you.

Formerly diffle

nittle used to be called diffle, and before that loupe. The old diffle.dev/install links still work: diffle.dev redirects to nittle.dev with the path kept. If you have a diffle install, the installer migrates it. See Migrating from diffle.

Custom location

Set NITTLE_INSTALL_DIR before running the installer to choose a different directory. DIFFLE_INSTALL_DIR is still read as a fallback.

PATH on macOS / Linux

The installer appends a marked block to your login shell’s rc file: .zshrc for zsh (under ZDOTDIR if set), .bashrc for bash (plus a .bash_profile that sources it on macOS), config.fish for fish, .profile for anything else.

# >>> nittle >>>
export PATH="$HOME/.nittle/bin:$PATH"
# <<< nittle <<<

Nothing else in the file is reordered or rewritten. The file is copied to <rc>.nittle.bak-<timestamp> before the first edit, and re-running the installer is a no-op. A child process can’t change the shell that launched it, so run exec $SHELL -l (fish: source <rc>) to use nittle right away. New shells pick it up on their own.

Set NITTLE_NO_MODIFY_PATH=1 to skip the rc edit and print the export line instead, NITTLE_NO_SETUP=1 to skip the agent setup prompt, or NITTLE_DRY_RUN=1 to log every intended change without writing anything.

Windows PATH

install.ps1 needs PowerShell 7 or newer. It edits only your user PATH, never the machine scope and never the merged process value. It backs the old value up to a timestamped file in your temp directory first, keeps every existing entry (%VAR% tokens included), and does nothing if ~\.nittle\bin is already there. Set NITTLE_NO_MODIFY_PATH to install without touching PATH, NITTLE_NO_SETUP to skip the agent setup prompt, or NITTLE_DRY_RUN to print the plan and write nothing.

If you have a diffle install

Run the same installer. After it installs nittle, it runs nittle --version once, and the binary’s own first-run migration moves everything over: the data directory, the install directory and PATH entry, the agent plugins and MCP configs, and the browser prefs. Then it removes the diffle leftovers.

The installer also finds a diffle that was installed to a custom directory. It reads the directory from the old # >>> diffle >>> block in your rc file or from PATH, and only trusts a directory that really holds a diffle binary.

If the migration can’t finish, nittle keeps both copies, prints what is left, and tries again on the next run. Details are in Migrating from diffle.

Set up your coding agents

On a terminal, the installer finishes by asking Set up nittle for your coding agents? [Y/n] and runs nittle setup. It detects the agents you have installed, shows exactly what it will change, and asks before applying. You can run it any time, and nittle setup --remove undoes it. See Agent feedback.

nittle setup

The prompt is skipped when there’s no terminal, with NITTLE_DRY_RUN, or with NITTLE_NO_SETUP=1.

Verify

1. Open a new terminal so PATH changes take effect.

2. Check the version:

   nittle --version

3. From any git repository, start a review:

   nittle

   nittle prints a http://127.0.0.1:<port> URL and opens it in your browser.

Keep it current

nittle update

nittle update downloads the latest release, verifies its checksum, and swaps the binary in place (on Windows the swap completes as the process exits). If a package manager installed nittle, it prints that manager’s upgrade command instead.

nittle also announces a new release in one line when you launch a review (at most one check a day). Set NITTLE_NO_UPDATE_CHECK=1 to silence it, or run nittle update --check to ask on demand.

Uninstall

The uninstaller removes the binary and its PATH entry, and any diffle leftovers too. On a terminal, it first runs nittle setup --remove so agents you wired up with nittle setup stop pointing at the deleted binary. Cancelling that stops the uninstall with the binary still in place. Set NITTLE_NO_SETUP=1 to skip it. Without a terminal, run nittle setup --remove yourself before uninstalling.

It only removes empty directories. Your review records and settings stay in ~/.nittle until you delete them.

macOS / Linux

curl -fsSL https://nittle.dev/install | sh -s -- --uninstall   # binary + PATH block
rm -rf ~/.nittle                                              # also removes review records + settings

The uninstall step removes the # >>> nittle >>> block from your rc file (and the old # >>> diffle >>> block, if there is one) and leaves the rest byte-identical. If you already have the script on disk, sh install.sh --uninstall does the same thing. NITTLE_UNINSTALL=1 works too.

Windows

$env:NITTLE_UNINSTALL = 1                 # the binary, and its user PATH entry
irm https://nittle.dev/install.ps1 | iex
Remove-Item -Recurse -Force ~/.nittle     # also removes review records + settings

From source (contributors)

nittle’s server, CLI, and MCP runtime run on Bun. The client is a built Svelte SPA.

git clone https://github.com/codywilliamson/diffle
cd diffle
bun install
bun run dev        # backend + Vite with /api proxied