Environment Variables

AI/Chat Configuration

Mu uses Anthropic Claude for all AI features.

export ANTHROPIC_API_KEY="your-anthropic-api-key"
export ANTHROPIC_MODEL="claude-sonnet-4-20250514"  # Default model

YouTube Configuration

# YouTube API key for video functionality
export YOUTUBE_API_KEY="your-youtube-api-key"

Places Configuration

# Google Places API key for enhanced places search and nearby POI lookup
# Optional: falls back to OpenStreetMap/Overpass when not set
export GOOGLE_API_KEY="your-google-places-api-key"

Notes:

• When GOOGLE_API_KEY is set, Places uses the Google Places API (New) for search and nearby queries
• Without it, Places falls back to free OpenStreetMap/Overpass and Nominatim data
• Enable the Places API (New) in Google Cloud Console; the YouTube Data API key is separate

ActivityPub Configuration

# Domain for ActivityPub federation (user discovery, actor URLs)
export MU_DOMAIN="yourdomain.com"  # Falls back to MAIL_DOMAIN, then "localhost"

Note: This must match your public domain so remote servers can resolve your users. See ActivityPub for details.

Messaging Configuration

Mu supports sending and receiving external email via SMTP.

# SMTP server port for receiving external email
export MAIL_PORT="2525"              # Default: 2525 (use 25 for production)

# Domain for email addresses
export MAIL_DOMAIN="yourdomain.com"  # Default: localhost

# DKIM signing selector
export MAIL_SELECTOR="default"       # Default: default

# DKIM private key (PEM format). Takes precedence over ~/.mu/keys/dkim.key
export DKIM_PRIVATE_KEY="-----BEGIN RSA PRIVATE KEY-----\n..."

Notes:

• SMTP configuration only needed for external email (sending/receiving outside Mu)
• Mu delivers external messages directly to recipient servers via SMTP (no relay needed)
• DKIM signing enables automatically when DKIM_PRIVATE_KEY is set, or if a key file exists at ~/.mu/keys/dkim.key
• DKIM_PRIVATE_KEY takes precedence over the key file (useful in Docker/cloud deployments)
• External email costs credits (SMTP delivery cost)

Stripe Configuration (Optional)

Enable card payments via Stripe for topping up credits.

# Stripe keys (optional - for card payments)
export STRIPE_SECRET_KEY="sk_live_..."
export STRIPE_PUBLISHABLE_KEY="pk_live_..."
export STRIPE_WEBHOOK_SECRET="whsec_..."  # For verifying Stripe webhook events

Notes:

• When empty, card payment option is hidden on the top-up page
• Configure a Stripe webhook pointing to /wallet/stripe/webhook to credit users after payment
• Supported events: checkout.session.completed

x402 Payments (Optional)

Enable cryptocurrency payments via the x402 protocol. External clients (AI agents, apps) can pay per-request with stablecoins instead of needing a Mu account.

# Wallet address to receive payments (required to enable x402)
export X402_PAY_TO="0xYourWalletAddress"

# Accepted tokens (comma-separated symbols). Default: USDC,EURC
export X402_ASSETS="USDC,EURC"

# Facilitator URL for payment verification and settlement
export X402_FACILITATOR_URL="https://x402.org/facilitator"  # Default

# Blockchain network identifier
export X402_NETWORK="eip155:8453"  # Default: Base mainnet

Notes:

• Only X402_PAY_TO is required — everything else has sensible defaults
• USDC and EURC on Base are accepted by default
• X402_ASSETS overrides the default tokens (e.g. "USDC" for USDC only)
• X402_ASSET (single contract address) still works for backwards compatibility
• When enabled, API clients can send X-PAYMENT header instead of authenticating
• Payments settle on-chain via the facilitator — no Stripe needed
• Credit costs are converted to USD at 1 credit = $0.01

Payment Configuration (Optional)

Enable donations to support your instance. All variables are optional - leave empty for a free instance.

# One-time donation URL
export DONATION_URL="https://gocardless.com/your-donation-link"

Notes:

• When empty, donation features are hidden
• Links appear on /donate page

Quota Configuration

# Daily free AI queries (default: 10)
export FREE_DAILY_QUOTA="10"

# Credit costs per operation (default values shown)
export CREDIT_COST_NEWS="1"        # News search (1p)
export CREDIT_COST_VIDEO="2"       # Video search (2p) - YouTube API cost
export CREDIT_COST_VIDEO_WATCH="0" # Video watch (free) - no value added over YouTube
export CREDIT_COST_CHAT="3"        # Chat AI query (3p) - LLM cost
export CREDIT_COST_EMAIL="4"       # External email (4p) - SMTP delivery cost
export CREDIT_COST_PLACES_SEARCH="5"  # Places text search (5p) - Google Places API cost
export CREDIT_COST_PLACES_NEARBY="2"  # Nearby places lookup (2p) - Google Places API cost

Notes:

• 1 credit = £0.01 (1 penny)
• Admins get unlimited access (no quotas)
• Credits never expire

Example Usage

Development (Local Testing)

# Messaging server on port 2525
export MAIL_PORT="2525"
export MAIL_DOMAIN="localhost"

./mu --serve --address :8080

Production

# Messaging server on standard SMTP port 25
export MAIL_PORT="25"

# Your domain and DKIM configuration
export MAIL_DOMAIN="yourdomain.com"
export MAIL_SELECTOR="default"

./mu --serve --address :8080

All Environment Variables

.env File (Optional)

Create a .env file:

# AI/Chat
ANTHROPIC_API_KEY=your-anthropic-api-key

# YouTube
YOUTUBE_API_KEY=your-youtube-api-key

# Places (optional - falls back to OpenStreetMap without this)
# GOOGLE_API_KEY=your-google-places-api-key

# Messaging (uses SMTP protocol)
MAIL_PORT=2525
MAIL_DOMAIN=yourdomain.com
MAIL_SELECTOR=default

# Stripe card payments (optional)
# STRIPE_SECRET_KEY=sk_live_...
# STRIPE_PUBLISHABLE_KEY=pk_live_...
# STRIPE_WEBHOOK_SECRET=whsec_...

# Donations (optional - leave empty for free instance)
DONATION_URL=https://gocardless.com/your-donation-link

Load and run:

export $(cat .env | xargs) && ./mu --serve --address :8080

Systemd Service Example

[Unit]
Description=Mu Service
After=network.target

[Service]
Type=simple
User=mu
WorkingDirectory=/opt/mu

# AI/Chat
Environment="ANTHROPIC_API_KEY=your-anthropic-api-key"

# YouTube
Environment="YOUTUBE_API_KEY=your-youtube-api-key"

# Messaging
Environment="MAIL_PORT=25"
Environment="MAIL_DOMAIN=yourdomain.com"
Environment="MAIL_SELECTOR=default"
Environment="DKIM_PRIVATE_KEY=-----BEGIN RSA PRIVATE KEY-----\n..."

# Donations (optional)
Environment="DONATION_URL=https://gocardless.com/your-donation-link"

ExecStart=/opt/mu/mu --serve --address :8080
Restart=always

[Install]
WantedBy=multi-user.target

Docker Example

FROM golang:1.24 AS builder
WORKDIR /app
COPY . .
RUN go build -o mu

FROM debian:bookworm-slim
COPY --from=builder /app/mu /usr/local/bin/
EXPOSE 8080 25
CMD ["mu", "--serve", "--address", ":8080"]

Run with environment variables:

docker run -d \
  -p 8080:8080 \
  -p 25:25 \
  -e ANTHROPIC_API_KEY=your-anthropic-api-key \
  -e YOUTUBE_API_KEY=your-youtube-api-key \
  -e MAIL_PORT=25 \
  -e MAIL_DOMAIN=yourdomain.com \
  -e MAIL_SELECTOR=default \
  -e DONATION_URL=https://gocardless.com/your-donation-link \
  -v ~/.mu:/root/.mu \
  mu:latest

Getting API Keys

Anthropic API

• Sign up at Anthropic
• Get your API key from the Console
• Required for all AI features (chat, digest, summaries)

YouTube API

1. Go to Google Cloud Console
2. Create a new project
3. Enable YouTube Data API v3
4. Create credentials (API Key)
5. Required for video search/playback

Google Places API

1. Go to Google Cloud Console
2. Create or reuse a project
3. Enable Places API (New)
4. Create credentials (API Key)
5. Optional — Places falls back to OpenStreetMap/Overpass without it

Feature Requirements