Claude Code in your browser#

This page runs Claude Code in a Linux machine inside your browser tab. The machine is compiled to WebAssembly (wmd-web) and starts from the Docker image chatwork/claude-code:2.1.316: Debian bookworm with Claude Code installed by Anthropic's install script. Nothing runs on a server. The machine reaches the internet, including Claude's API, through the relay. The relay carries encrypted TLS traffic and cannot read it.

1. Start the machine#

Press Run. The first run starts the machine. The block also writes Claude Code's settings file, ~/.claude.json, marking the first-run setup as done and trusting the home folder, so claude opens straight to its prompt. It leaves a settings file that already records the setup as done. It also writes four settings to ~/.claude-env, which ~/.bashrc loads, that make Claude Code start faster in this machine: only Claude Code's own CA certificates, no non-essential network traffic, and the JavaScript engine's two top compilers off (their code is costly to translate in a WebAssembly machine).

grep -qs hasCompletedOnboarding ~/.claude.json || cat > ~/.claude.json <<EOF
{
  "hasCompletedOnboarding": true,
  "theme": "dark",
  "projects": { "$HOME": { "hasTrustDialogAccepted": true, "hasCompletedProjectOnboarding": true } }
}
EOF
echo 'export CLAUDE_CODE_CERT_STORE=bundled CLAUDE_CODE_DISABLE_NONESSENTIAL_TRAFFIC=1 BUN_JSC_useDFGJIT=0 BUN_JSC_useFTLJIT=0' > ~/.claude-env
grep -qs claude-env ~/.bashrc || echo '. ~/.claude-env' >> ~/.bashrc
uname -m
claude --version

2. Sign in and start Claude Code#

Open Terminal at the top of the page and press New terminal. It is a shell in the same machine. Run this line, then paste your token and press Enter. Nothing shows while you paste:

read -rs CLAUDE_CODE_OAUTH_TOKEN && export CLAUDE_CODE_OAUTH_TOKEN

Then start Claude Code:

cd ~ && claude

To make a token, run claude setup-token on a computer where Claude Code is installed. An Anthropic API key works too: use ANTHROPIC_API_KEY in place of CLAUDE_CODE_OAUTH_TOKEN. The token stays in the machine in your tab. When you close the tab, the machine and everything in it are gone.

3. Ask from a block#

Blocks run in their own shell, so they do not see the terminal's variables. To let this block use your token, first run this in the terminal (it writes a file only you can read):

(umask 077; printf %s "$CLAUDE_CODE_OAUTH_TOKEN" > ~/.claude-token)

. ~/.claude-env
export CLAUDE_CODE_OAUTH_TOKEN="$(cat ~/.claude-token)"
cd ~ && claude -p "Run uname -a and tell me in one sentence what machine you are on." --allowedTools "Bash(uname:*)"