blit

Terminal streaming for browsers and AI agents. One binary, nothing to configure.

Try it now — no install needed:

docker run --rm grab/blit-demo

Or install and run locally:

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

Share a terminal over WebRTC:

blit share # prints a URL anyone can open

Connect to a remote host over SSH:

blit --ssh myhost

Control terminals programmatically:

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

The server auto-starts when needed.

Install

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

macOS (Homebrew)

brew install indent-com/tap/blit

Debian / Ubuntu (APT)

curl -fsSL https://install.blit.sh/blit.gpg | sudo gpg --dearmor -o /usr/share/keyrings/blit.gpg
echo "deb [signed-by=/usr/share/keyrings/blit.gpg arch=$(dpkg --print-architecture)] https://install.blit.sh/ stable main" \
  | sudo tee /etc/apt/sources.list.d/blit.list
sudo apt update && sudo apt install blit

Nix

nix profile install github:indent-com/blit#blit

Or jump to nix-darwin / NixOS for service configuration.

From source

nix develop # or use direnv — .envrc is included
cargo build --release -p blit-cli

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.

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 session gets full frame rate; background sessions throttle down. Keystrokes go straight to the PTY — latency is bounded by link RTT.

blit 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 is the React integration library.

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

CLI subcommands

All subcommands auto-start a local server if needed. For remote hosts, use --ssh HOST, --tcp HOST:PORT, or --share PASSPHRASE.

blit list                                # List all PTYs (TSV: ID, TAG, TITLE, STATUS)
blit start htop                          # Start a PTY running htop, print its ID
blit start -t build make -j8             # Start with a tag
blit start --rows 40 --cols 120 bash     # Start with a custom size
blit start --wait --timeout 60 make -j8  # Start and block until exit
blit show 3                              # Dump current visible terminal text
blit show 3 --ansi                       # Include ANSI color/style codes
blit history 3                           # Dump all scrollback + viewport
blit history 3 --from-start 0 --limit 50 # First 50 lines
blit history 3 --from-end 0 --limit 50   # Last 50 lines
blit send 3 "q"                          # Send keystrokes (supports \n, \t, \x1b escapes)
blit show 3 --rows 40 --cols 120         # Resize before capturing viewport
blit history 3 --cols 200                # Resize before reading scrollback
blit wait 3 --timeout 30                 # Block until session exits
blit wait 3 --timeout 60 --pattern DONE  # Block until output matches regex
blit restart 3                           # Restart an exited session
blit close 3                             # Close and remove a PTY

blit share                               # Share via WebRTC (prints URL)
blit share --passphrase mysecret         # Share with a specific passphrase
blit share --verbose                     # Share with connection diagnostics

blit upgrade                             # Upgrade blit to the latest version

blit --ssh myhost list                   # Against a remote host
blit --ssh myhost start htop
blit --ssh myhost show 1

Output is plain text with no decoration — designed to be easy for scripts and LLMs to parse. Errors go to stderr; non-zero exit on failure.

If you're building an AI agent that drives terminals, SKILLS.md is a ready-made skill definition you can drop into your agent's tool list.

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_SCROLLBACK	10000	Scrollback rows per PTY
BLIT_HUB	hub.blit.sh	Signaling hub URL for WebRTC sharing

blit-gateway (optional, for persistent multi-user browser access)

Variable	Default	Purpose
BLIT_PASS	required	Browser passphrase
BLIT_ADDR	0.0.0.0:3264	HTTP/WebSocket listen address
BLIT_SOCK	$TMPDIR/blit.sock, $XDG_RUNTIME_DIR/blit.sock, or /tmp/blit-$USER.sock	Upstream server socket
BLIT_CORS	unset	CORS origin for font routes
BLIT_QUIC	unset	Set to 1 to enable WebTransport
BLIT_TLS_CERT	auto-generated	TLS cert for WebTransport
BLIT_TLS_KEY	auto-generated	TLS key for WebTransport

Running as a service

macOS (Homebrew)

brew services start blit-server
brew services start blit-gateway

Debian / Ubuntu (systemd)

sudo systemctl enable --now blit-server@alice.socket

# Share via WebRTC: create /etc/blit/forwarder-alice.env with
# BLIT_SOCK=/run/blit/alice.sock and BLIT_PASSPHRASE=<secret>, then:
sudo systemctl enable --now blit-webrtc-forwarder@alice.service

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)	✅	❌	❌	❌	❌	✅
Agent / CLI subcommands	✅	❌	❌	❌	❌	❌
SSH tunneling built-in	✅	❌	❌	✅	✅	❌

What lives in this repo

Directory	Package	Role
crates/cli/	blit	Browser client, agent subcommands, SSH tunnels, server/share
crates/server/	blit-server	PTY host and frame scheduler (also embedded in blit)
crates/gateway/	blit-gateway	WebSocket/WebTransport proxy for multi-user access
crates/webrtc-forwarder/	blit-webrtc-forwarder	WebRTC bridge for NAT traversal (STUN/TURN)
crates/remote/	blit-remote	Wire protocol and frame/state primitives
crates/browser/	blit-browser	WASM terminal runtime
crates/alacritty-driver/	blit-alacritty	Terminal parsing backed by alacritty_terminal
crates/fonts/	blit-fonts	Font discovery and metadata
crates/webserver/	blit-webserver	Shared HTTP helpers for serving assets and fonts
js/react/	@blit-sh/react	React client library (EMBEDDING.md)
js/web-app/		Browser UI

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.

Docker sandbox

The grab/blit-demo image runs unprivileged and launches blit share on startup. It includes fish, busybox, htop, neovim, git, curl, jq, tree, and ncdu.

To build locally:

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

nix-darwin

{ inputs, ... }: {
  imports = [ inputs.blit.darwinModules.blit ];

  services.blit = {
    enable = true;
    gateways.default = {
      port = 3264;
      passFile = "/path/to/blit-pass-env";
    };
    forwarders.default = {
      passFile = "/path/to/blit-forwarder-env";
    };
  };
}

See nix/darwin-module.nix for the full list of options.

NixOS

{ inputs, ... }: {
  imports = [ inputs.blit.nixosModules.blit ];

  services.blit = {
    enable = true;
    users = [ "alice" "bob" ];
    gateways.alice = {
      user = "alice";
      port = 3264;
      passFile = "/run/secrets/blit-alice-pass";
    };
    forwarders.alice = {
      user = "alice";
      passFile = "/run/secrets/blit-alice-forwarder-pass";
    };
  };
}

See nix/nixos-module.nix for the full list of options.