blit

Terminal multiplexer and experimental Wayland compositor for browsers and AI agents. One binary, nothing to configure.

We publish a computer agent skill.

Try it now — no install needed:

docker run --rm grab/blit-demo

Or install and run locally:

curl -sf https://install.blit.sh | sh
blit open # opens a browser

Share a terminal over WebRTC:

blit share # prints a URL anyone can open

Manage named remotes and connect to them:

blit remote add rabbit ssh:rabbit          # save a named remote
blit remote add prod ssh:alice@prod.co     # another one
blit remote list                           # show all remotes
blit remote set-default rabbit             # make rabbit the default

blit open                                  # local + all configured remotes
blit terminal list                         # lists terminals on rabbit
blit --on prod terminal list               # one-off override
blit --on ssh:newhost terminal list        # full URI also works

The default remote is stored in ~/.config/blit/blit.conf as blit.target = rabbit and can also be set via the BLIT_TARGET environment variable. Named remotes are stored in ~/.config/blit/blit.remotes (mode 0600). blit open reads this file and shows all remotes in the browser's Remotes dialog (Cmd+K). SSH remotes are auto-installed on first connection.

Control terminals programmatically:

blit terminal start htop # start a terminal, print its ID
blit terminal show 1     # dump current terminal text
blit terminal send 1 q   # send keystrokes

Run GUI apps — on Linux, every terminal includes an experimental headless Wayland compositor:

blit terminal start foot    # launch a Wayland terminal emulator
blit surface list           # list graphical windows
blit surface capture 1      # screenshot a surface
blit surface click 1 100 50 # click at (x, y)
blit surface type 1 "hello{Return}" # type into a GUI window

The server auto-starts when needed.

Supported platforms

Platform	Arch	Wayland compositor	Notes
Linux	x86_64, arm64	Yes	Full features
macOS	arm64	No	PTY multiplexing only
Windows	x86_64	No	PTY multiplexing only

SSH remotes are auto-installed on first connection. Requirements on the remote: curl or wget, CA certificates, and a supported OS/arch.

The embedded SSH client authenticates via ssh-agent (SSH_AUTH_SOCK) or key files (~/.ssh/id_{ed25519,ecdsa,rsa}), and resolves ~/.ssh/config for Hostname, User, Port, and IdentityFile.

Install

curl -sf https://install.blit.sh | sh

Windows (PowerShell)

irm https://install.blit.sh/install.ps1 | iex

This downloads blit.exe to %LOCALAPPDATA%\blit\bin and adds it to your user PATH. Set BLIT_INSTALL_DIR to override the install location.

How it works

blit hosts PTYs and tracks full parsed terminal state. For each connected browser it computes a binary diff against what that browser last saw and sends only the delta — LZ4-compressed, with scrolling encoded as copy-rect operations. WebGL-rendered in the browser.

On Linux, every blit server includes an experimental headless Wayland compositor shared by all terminals. GUI applications launched inside any terminal (anything that speaks the Wayland protocol — terminal emulators, browsers, editors, media players) automatically connect to it. Surfaces are captured, encoded as H.264 or AV1 video, and streamed to connected browsers in real time. No X server, no display, no GPU required — rendering uses GPU compositing (Vulkan via dlopen) when available, with a CPU software fallback. Encoding uses openh264/rav1e (with optional NVENC or VA-API hardware acceleration on Linux). The compositor is available on Linux only.

Each client is paced independently based on render metrics it reports back: display rate, frame apply time, backlog depth. A phone on 3G doesn't stall a workstation on localhost. The focused terminal gets full frame rate; background terminals throttle down. Keystrokes go straight to the PTY — latency is bounded by link RTT.

blit open opens the browser with an embedded gateway. For persistent multi-user browser access, blit gateway is a standalone proxy that handles passphrase auth, serves the web app, and optionally enables QUIC. blit server can also run standalone for headless/daemon use. For embedding in your own app, @blit-sh/react and @blit-sh/solid provide framework bindings.

blit proxy-daemon is a connection pool that makes remote connections feel local. It runs as a persistent background daemon per user session, maintaining pre-warmed connections to each upstream target so browser tabs connect instantly without paying SSH negotiation or TCP handshake cost. The proxy auto-starts transparently on Unix and Windows — set BLIT_PROXY=0 to opt out.

For wire protocol details, frame encoding, and transport internals, see ARCHITECTURE.md.

Configuration

Variable	Default	Purpose
BLIT_SOCK	$TMPDIR/blit.sock, /tmp/blit-$USER.sock, /run/blit/$USER.sock, $XDG_RUNTIME_DIR/blit.sock, or /tmp/blit.sock	Unix socket path
BLIT_TARGET	unset	Default remote: a URI or named remote (overrides target in blit.conf)
BLIT_REMOTES	~/.config/blit/blit.remotes	Gateway remotes file path (overrides default location)
BLIT_SCROLLBACK	10000	Scrollback rows per PTY
BLIT_HUB	hub.blit.sh	Signaling hub URL for WebRTC sharing. On blit gateway, sets the default hub for share: remotes when BLIT_GATEWAY_WEBRTC=1.
BLIT_GATEWAY_WEBRTC	unset	Set to 1 on blit gateway to proxy share: remotes via WebRTC. The gateway connects as a WebRTC consumer and bridges terminals to browsers over WebSocket/WebTransport. Without this, share: entries in blit.remotes are ignored.
BLIT_INSTALL_DIR	%LOCALAPPDATA%\blit\bin (Windows)	Override install location (Windows PowerShell installer)
BLIT_SURFACE_ENCODERS	see below	Comma-separated encoder priority list (see below)
BLIT_SURFACE_QUALITY	medium	Video quality preset: low, medium, high, lossless
BLIT_VAAPI_DEVICE	/dev/dri/renderD128	VA-API render node for hardware-accelerated encoding
BLIT_CUDA_DEVICE	0	CUDA device ordinal for NVENC hardware encoding

Surface video encoders

Set BLIT_SURFACE_ENCODERS to a comma-separated priority list of encoders. The server tries each in order and uses the first that works.

# Default priority (hardware before software):
# av1-nvenc,h264-nvenc,av1-vaapi,h264-vaapi,h264-software,av1-software

# Force software AV1 only:
BLIT_SURFACE_ENCODERS=av1-software

# Prefer NVENC, fall back to software:
BLIT_SURFACE_ENCODERS=av1-nvenc,h264-nvenc,h264-software

Value	Codec	Backend	Notes
av1-nvenc	AV1	NVIDIA NVENC	RTX 40+ series; fastest AV1 encode
h264-nvenc	H.264	NVIDIA NVENC	Requires proprietary NVIDIA driver
av1-vaapi	AV1	VA-API	Intel/AMD GPU
h264-vaapi	H.264	VA-API	Intel/AMD GPU; max 3840×2160
h264-software	H.264	openh264	Max 3840×2160; lowest CPU but worst compression
av1-software	AV1	rav1e (software)	No resolution limit; CPU-heavy at high res

The browser automatically detects the codec from each frame and configures its WebCodecs decoder accordingly. Clients can also advertise which codecs they support; the server skips encoders the client can't decode.

For blit gateway configuration, running as a systemd/launchd service, and Nix module setup, see SERVICES.md and nix/README.md.

How it compares

	blit	ttyd	gotty	Eternal Terminal	Mosh	xterm.js + node-pty
Architecture	Single binary	Single binary	Single binary	Client + daemon	Client + server	Library (BYO server)
Multiple PTYs	✅ First-class	❌ One per instance	❌ One per instance	❌ One per connection	❌ One per connection	⚠️ Manual
Browser access	✅	✅	✅	❌	❌	✅
Delta updates	✅ Only changed cells	❌	❌	❌	✅ State diffs	❌
LZ4 compression	✅	❌	❌	❌	❌	❌
Per-client backpressure	✅ Render-metric pacing	❌	❌	⚠️ SSH flow control	❌	❌
WebGL rendering	✅	❌	❌	❌	❌	⚠️ Addon
Transport	WS, WebTransport, WebRTC, Unix	WebSocket	WebSocket	TCP	UDP	WebSocket
Embeddable (React/Solid)	✅	❌	❌	❌	❌	✅
Wayland compositor	✅ Built-in headless (experimental)	❌	❌	❌	❌	❌
GUI app streaming	✅ H.264 / AV1	❌	❌	❌	❌	❌
Agent / CLI subcommands	✅	❌	❌	❌	❌	❌
SSH tunneling built-in	✅	❌	❌	✅	✅	❌

Browser tips

Disable Ctrl+W tab close (Chrome / Brave / Edge)

When using blit in the browser, Ctrl+W closes the browser tab instead of reaching your terminal. Chromium-based browsers let you disable this:

1. Navigate to chrome://settings/system/shortcuts (or brave://settings/system/shortcuts in Brave)
2. Find the Close Tab shortcut and remove or reassign it

This frees Ctrl+W for terminal use (e.g. deleting a word in bash/zsh).

Contributing

Building from source, running tests, dev environment setup, code conventions, and release process are all covered in CONTRIBUTING.md. CI/CD pipelines, the install site, and the signaling hub are documented in SERVICES.md. The crate and package map is in ARCHITECTURE.md.

Docker sandbox

The grab/blit-demo image runs unprivileged and launches blit share on startup. It includes blit itself, plus fish, busybox, htop, neovim, git, curl, jq, tree, ncdu, and Wayland GUI apps (foot, mpv, imv, zathura, wev).

To build locally:

nix build .#demo-image
docker load < result
docker run --rm grab/blit-demo