hermes-agent/website/docs/user-guide/messaging/whatsapp.md

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5	WhatsApp	Set up Hermes Agent as a WhatsApp bot via the built-in Baileys bridge

WhatsApp Setup

Hermes connects to WhatsApp through a built-in bridge based on Baileys. This works by emulating a WhatsApp Web session — not through the official WhatsApp Business API. No Meta developer account or Business verification is required.

:::warning Unofficial API — Ban Risk WhatsApp does not officially support third-party bots outside the Business API. Using a third-party bridge carries a small risk of account restrictions. To minimize risk:

• Use a dedicated phone number for the bot (not your personal number)
• Don't send bulk/spam messages — keep usage conversational
• Don't automate outbound messaging to people who haven't messaged first :::

:::warning WhatsApp Web Protocol Updates WhatsApp periodically updates their Web protocol, which can temporarily break compatibility with third-party bridges. When this happens, Hermes will update the bridge dependency. If the bot stops working after a WhatsApp update, pull the latest Hermes version and re-pair. :::

Two Modes

Mode	How it works	Best for
Separate bot number (recommended)	Dedicate a phone number to the bot. People message that number directly.	Clean UX, multiple users, lower ban risk
Personal self-chat	Use your own WhatsApp. You message yourself to talk to the agent.	Quick setup, single user, testing

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Prerequisites

• Node.js v18+ and npm — the WhatsApp bridge runs as a Node.js process
• A phone with WhatsApp installed (for scanning the QR code)

Unlike older browser-driven bridges, the current Baileys-based bridge does not require a local Chromium or Puppeteer dependency stack.

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Step 1: Run the Setup Wizard

hermes whatsapp

The wizard will:

1. Ask which mode you want (bot or self-chat)
2. Install bridge dependencies if needed
3. Display a QR code in your terminal
4. Wait for you to scan it

To scan the QR code:

1. Open WhatsApp on your phone
2. Go to Settings → Linked Devices
3. Tap Link a Device
4. Point your camera at the terminal QR code

Once paired, the wizard confirms the connection and exits. Your session is saved automatically.

:::tip If the QR code looks garbled, make sure your terminal is at least 60 columns wide and supports Unicode. You can also try a different terminal emulator. :::

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Step 2: Getting a Second Phone Number (Bot Mode)

For bot mode, you need a phone number that isn't already registered with WhatsApp. Three options:

Option	Cost	Notes
Google Voice	Free	US only. Get a number at voice.google.com. Verify WhatsApp via SMS through the Google Voice app.
Prepaid SIM	$5–15 one-time	Any carrier. Activate, verify WhatsApp, then the SIM can sit in a drawer. Number must stay active (make a call every 90 days).
VoIP services	Free–$5/month	TextNow, TextFree, or similar. Some VoIP numbers are blocked by WhatsApp — try a few if the first doesn't work.

After getting the number:

1. Install WhatsApp on a phone (or use WhatsApp Business app with dual-SIM)
2. Register the new number with WhatsApp
3. Run hermes whatsapp and scan the QR code from that WhatsApp account

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Step 3: Configure Hermes

Add the following to your ~/.hermes/.env file:

# Required
WHATSAPP_ENABLED=true
WHATSAPP_MODE=bot                          # "bot" or "self-chat"
WHATSAPP_ALLOWED_USERS=15551234567         # Comma-separated phone numbers (with country code, no +)

Optional behavior settings in ~/.hermes/config.yaml:

unauthorized_dm_behavior: pair

whatsapp:
  unauthorized_dm_behavior: ignore

• unauthorized_dm_behavior: pair is the global default. Unknown DM senders get a pairing code.
• whatsapp.unauthorized_dm_behavior: ignore makes WhatsApp stay silent for unauthorized DMs, which is usually the better choice for a private number.

Then start the gateway:

hermes gateway              # Foreground
hermes gateway install      # Install as a user service
sudo hermes gateway install --system   # Linux only: boot-time system service

The gateway starts the WhatsApp bridge automatically using the saved session.

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Session Persistence

The Baileys bridge saves its session under ~/.hermes/whatsapp/session. This means:

• Sessions survive restarts — you don't need to re-scan the QR code every time
• The session data includes encryption keys and device credentials
• Do not share or commit this session directory — it grants full access to the WhatsApp account

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Re-pairing

If the session breaks (phone reset, WhatsApp update, manually unlinked), you'll see connection errors in the gateway logs. To fix it:

hermes whatsapp

This generates a fresh QR code. Scan it again and the session is re-established. The gateway handles temporary disconnections (network blips, phone going offline briefly) automatically with reconnection logic.

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Voice Messages

Hermes supports voice on WhatsApp:

• Incoming: Voice messages (.ogg opus) are automatically transcribed using the configured STT provider: local faster-whisper, Groq Whisper (GROQ_API_KEY), or OpenAI Whisper (VOICE_TOOLS_OPENAI_KEY)
• Outgoing: TTS responses are sent as MP3 audio file attachments
• Agent responses are prefixed with "⚕ Hermes Agent" by default. You can customize or disable this in config.yaml:

# ~/.hermes/config.yaml
whatsapp:
  reply_prefix: ""                          # Empty string disables the header
  # reply_prefix: "🤖 *My Bot*\n──────\n"  # Custom prefix (supports \n for newlines)

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Troubleshooting

Problem	Solution
QR code not scanning	Ensure terminal is wide enough (60+ columns). Try a different terminal. Make sure you're scanning from the correct WhatsApp account (bot number, not personal).
QR code expires	QR codes refresh every ~20 seconds. If it times out, restart hermes whatsapp.
Session not persisting	Check that ~/.hermes/whatsapp/session exists and is writable. If containerized, mount it as a persistent volume.
Logged out unexpectedly	WhatsApp unlinks devices after long inactivity. Keep the phone on and connected to the network, then re-pair with hermes whatsapp if needed.
Bridge crashes or reconnect loops	Restart the gateway, update Hermes, and re-pair if the session was invalidated by a WhatsApp protocol change.
Bot stops working after WhatsApp update	Update Hermes to get the latest bridge version, then re-pair.
macOS: "Node.js not installed" but node works in terminal	launchd services don't inherit your shell PATH. Run hermes gateway install to re-snapshot your current PATH into the plist, then hermes gateway start. See the Gateway Service docs for details.
Messages not being received	Verify WHATSAPP_ALLOWED_USERS includes the sender's number (with country code, no + or spaces).
Bot replies to strangers with a pairing code	Set whatsapp.unauthorized_dm_behavior: ignore in ~/.hermes/config.yaml if you want unauthorized DMs to be silently ignored instead.

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Security

:::warning Always set WHATSAPP_ALLOWED_USERS with phone numbers (including country code, without the +) of authorized users. Without this setting, the gateway will deny all incoming messages as a safety measure. :::

By default, unauthorized DMs still receive a pairing code reply. If you want a private WhatsApp number to stay completely silent to strangers, set:

whatsapp:
  unauthorized_dm_behavior: ignore

• The ~/.hermes/whatsapp/session directory contains full session credentials — protect it like a password
• Set file permissions: chmod 700 ~/.hermes/whatsapp/session
• Use a dedicated phone number for the bot to isolate risk from your personal account
• If you suspect compromise, unlink the device from WhatsApp → Settings → Linked Devices
• Phone numbers in logs are partially redacted, but review your log retention policy