WhatsApp MCP Server

A single-binary Go MCP server that wraps whatsmeow to expose a personal WhatsApp account to LLMs. whatsapp-mcp serve runs as a lightweight HTTP daemon on 127.0.0.1:8765; MCP clients (Claude Desktop, Cursor, Claude Code, etc.) connect to it via HTTP — no process spawning, no stdin/stdout juggling. Messages are cached in local SQLite and only travel to the model when the agent calls a tool.

Unaffiliated. This is an independent open-source project. It is not affiliated with, endorsed by, or otherwise associated with Meta Platforms, Inc., WhatsApp, or whatsmeow. "WhatsApp" is a trademark of Meta Platforms, Inc., used here nominatively to describe interoperability.

This started as a fork of lharries/whatsapp-mcp and has since been rewritten as a single Go binary. What it adds over the original:

• LID resolution — normalises @lid JIDs to real phone numbers for accurate contact matching.
• Sent-message storage — outgoing messages are persisted locally so conversation history stays complete.
• Disappearing-message timers — outgoing messages inherit the group chat's ephemeral timer automatically.
• Targeted history sync — on-demand per-chat backfill via the request_sync tool.
• Extended tool surface — 42 tools (see below): reactions, replies, edits, revoke, mark-read, typing, is-on-whatsapp, full group admin, blocklist, polls (create + vote + tally), contact cards, view-once flag, presence, privacy settings, and the profile "About" text.
• Single-instance enforcement — a flock(2) on store/.lock prevents two serve processes racing on the same SQLite files.

Architecture

One binary, seven internal packages:

cmd/whatsapp-mcp/       login / serve / smoke subcommands
internal/client/        whatsmeow client wrapper (send, download, events, history, features)
internal/daemon/        HTTP server, pairing state machine, /pair endpoint
internal/mcp/           mark3labs/mcp-go server + tool registrations
internal/media/         ogg parsing, waveform synthesis, ffmpeg shell-out
internal/security/      path allowlisting, filename sanitisation, log redaction
internal/store/         SQLite cache, LID resolution, query layer

Process lifecycle

serve runs as a long-lived HTTP daemon. MCP clients connect and disconnect freely; the daemon stays up and continues receiving WhatsApp events. A flock(2) on store/.lock prevents two instances racing on the same store (WhatsApp would kick one of the two linked-device connections anyway).

The trade-off: events are persisted to SQLite only while serve is running. If the daemon stops, the WhatsApp connection closes. On the next start, whatsmeow emits events.HistorySync events that backfill conversations into SQLite, but the recovery window is governed by WhatsApp's server-side retention for multidevice clients — not by this codebase. Messages that arrive during a gap long enough to outlast WhatsApp's retention are not recoverable. For shorter, known gaps, the request_sync tool triggers a per-chat backfill on demand.

Data storage

Everything lives under ./store/ (override with -store DIR):

• store/messages.db — local chat/message cache, indexed for search.
• store/whatsapp.db — whatsmeow's own device/session state.
• store/.lock — ephemeral advisory lock for single-instance serve.

Data flow

1. The client sends a JSON-RPC tools/call to serve over HTTP.
2. The MCP layer dispatches to an internal handler.
3. The handler either queries the local SQLite store or calls whatsmeow directly (send, download, reactions, etc.).
4. Incoming WhatsApp events are persisted to the store in a background goroutine inside the same process, so query tools always see current state.

Running the daemon

The daemon is designed to run independently of any MCP client. Three supported lifecycle models:

macOS — launchd. Template at docs/launchd/com.sealjay.whatsapp-mcp.plist. Copy to ~/Library/LaunchAgents/, replace {{PATH_TO_REPO}} / {{STORE_DIR}} placeholders, launchctl load. Daemon runs from login onwards.

Linux — systemd user unit. Template at docs/systemd/whatsapp-mcp.service. Copy to ~/.config/systemd/user/, replace placeholders, systemctl --user enable --now whatsapp-mcp.

Claude Code SessionStart hook. For project-scoped lifetimes, drop docs/hooks/setup.sh into your project's .claude/hooks/ and configure settings.json to invoke it. The hook is idempotent — safe to run alongside launchd/systemd.

Manual. ./bin/whatsapp-mcp serve -addr 127.0.0.1:8765 in any terminal. Ctrl-C to stop.

First-time pairing happens in a browser: start the daemon, open http://127.0.0.1:8765/pair, scan the QR with your phone. No terminal required. WhatsApp's multidevice protocol rotates the linked-device session roughly every 20 days; when that happens, the /pair page serves a fresh QR automatically — visit it again and re-pair. The /pair/* endpoints are rate-limited (5 GET/min, 1 POST/min on /pair/reset) and CSRF-protected.

Flags and environment variables for serve:

• -addr host:port (env WHATSAPP_MCP_ADDR, default 127.0.0.1:8765).
• -allow-remote (explicit opt-in to bind a non-loopback address; requires WHATSAPP_MCP_TOKEN).
• WHATSAPP_MCP_TOKEN — bearer token for /mcp and /pair/* when -allow-remote is set. Required; serve exits if missing.
• WHATSAPP_MCP_MEDIA_ROOT — allowed root for send_file / send_audio_message media_path and download_media output_path.
• WHATSAPP_MCP_DEBUG=1 — enable verbose logging with partial phone-number redaction (last 5 digits visible).

Tools

42 tools, grouped by purpose.

Read / query

Send

Message actions

Groups

Blocklist

Privacy / presence / status

Admin

Deferred

Intentionally not exposed yet:

• subscribe_presence — no persistence layer for presence events, skipped to avoid a dangling tool.
• Profile photo setter — upstream whatsmeow doesn't expose a user-level setter.
• Approval-mode participants, communities, newsletters — low-use surface, deferred.

Development

make test          # unit tests
make test-race     # with -race
make vet           # go vet
make e2e           # build + JSON-RPC smoke over HTTP (requires -tags=e2e)
make smoke         # boot-test the server without connecting to WhatsApp

Upgrading whatsmeow

Weekly CI runs an upstream upgrade probe. To do it manually:

make upgrade-check

This bumps go.mau.fi/whatsmeow@main, re-tidies, builds, and tests. If green, commit the go.mod / go.sum changes.

scripts/mdtest-parity.sh in CI fails the build early if upstream removes or renames any whatsmeow method we call — it's the canary for API drift.

Setup

Prerequisites

• Go 1.25+ (build-time only; runtime needs just the compiled binary).
• An MCP client that speaks HTTP (Claude Desktop, Cursor, Claude Code, etc.).
• FFmpeg (optional) — required only for send_audio_message when the input is not already .ogg Opus. Without it, use send_file to send raw audio.
• Windows: CGO must be enabled — see docs/windows.md.

Install

git clone https://github.com/Sealjay/mcp-whatsapp.git
cd mcp-whatsapp
make build    # writes ./bin/whatsapp-mcp

Pair your phone (first run only)

Start the daemon, then open the pairing page in a browser:

./bin/whatsapp-mcp serve          # starts on 127.0.0.1:8765
open http://127.0.0.1:8765/pair   # macOS; or visit the URL manually

Scan the QR code with WhatsApp on your phone (Settings → Linked Devices → Link a Device). The pairing persists to ./store/whatsapp.db. When WhatsApp invalidates the session (roughly every 20 days), visit /pair again and re-scan.

Alternative (headless / CI): ./bin/whatsapp-mcp login renders the QR in the terminal. Use this when a browser isn't available.

Connect your MCP client

whatsapp-mcp serve is an HTTP daemon on 127.0.0.1:8765 (or $WHATSAPP_MCP_ADDR). MCP clients connect to it over HTTP:

// Claude Desktop — ~/Library/Application Support/Claude/claude_desktop_config.json
{
  "mcpServers": {
    "whatsapp": { "url": "http://127.0.0.1:8765/mcp" }
  }
}

// Claude Code — .claude/mcp.json (project) or ~/.claude/mcp.json (user)
{
  "mcpServers": {
    "whatsapp": { "type": "http", "url": "http://127.0.0.1:8765/mcp" }
  }
}

// Cursor — ~/.cursor/mcp.json
{
  "mcpServers": {
    "whatsapp": { "type": "http", "url": "http://127.0.0.1:8765/mcp" }
  }
}

Restart the client. WhatsApp appears as an available integration. Closing and reopening the client reconnects to the daemon — no process spawn, no per-session handshake, no stdin/stdout juggling.

Sending and receiving files

WHATSAPP_MCP_MEDIA_ROOT gates both directions of file movement:

• Sending — send_file and send_audio_message accept a media_path argument pointing at the file to send. The path must live under the allowed root.
• Receiving — download_media writes decrypted media to the daemon cache at <store>/<chat_jid>/. Passing the optional output_path argument additionally places the file at a caller-chosen location, which must also live under the allowed root. If a file already exists at output_path the call is a no-op.

By default the allowed root is ./store/uploads/ (resolved relative to your -store directory). On first run, serve creates it automatically; drop files you intend to send into it and point output_path here if you want to read incoming media from the same place.

To allow a different directory, set WHATSAPP_MCP_MEDIA_ROOT (absolute path) when starting the daemon:

WHATSAPP_MCP_MEDIA_ROOT=/Users/me/whatsapp-shared ./bin/whatsapp-mcp serve

Or add it to your launchd plist / systemd unit / shell profile so it persists across restarts.

Paths outside the allowed root are rejected with a clear error so Claude can ask you to move the file or update the env var. Symlinks inside the root are resolved before the check, so a symlink that points out of the root is also rejected. Do not place secrets inside the allowed root — the allowlist bounds what the tool can read or write, but anything inside is fair game.

Sandboxed clients (Claude.ai with Cowork, etc.)

Sandboxed MCP clients cannot read the daemon's local cache. To make downloaded media visible to them, point WHATSAPP_MCP_MEDIA_ROOT at a directory the client's sandbox can also read (a Cowork workspace mount, a shared volume, etc.), and tell the client to pass output_path on every download_media call into that root. A copy-pasteable system instruction:

When calling the WhatsApp MCP's download_media, always pass output_path set to a path under your shared workspace. Without it the decrypted file lands only in the daemon's local cache, which is outside your sandbox and unreadable. output_path must live under WHATSAPP_MCP_MEDIA_ROOT on the daemon side; the basename is yours to pick.

Limitations

• Prompt-injection risk: as with many MCP servers, this one is subject to the lethal trifecta. Prompt injection in incoming messages could lead to private data exfiltration — treat the tool surface accordingly.
• Re-authentication: WhatsApp may invalidate the linked-device session periodically; re-run ./bin/whatsapp-mcp login when that happens.
• Message gaps when serve isn't running: events only flow into SQLite while the binary is alive. Messages sent during an offline window are recovered on next reconnect only if WhatsApp's multidevice retention still holds them; for longer gaps use request_sync per chat, or accept the loss.
• Single instance per store: only one whatsapp-mcp serve can hold the store lock. Parallel MCP clients must point at different -store directories (and therefore different paired sessions).
• Windows: requires CGO and a C compiler — see docs/windows.md.
• Upstream bounds: message fetch/send is bounded by what whatsmeow supports against the WhatsApp web multidevice API.
• Log redaction is obfuscation, not anonymisation. Partial knowledge of your contacts allows correlation from the last 5 visible digits. Symlinks inside ./store/uploads/ are resolved before the path check so they cannot escape, but the root itself is a trust boundary — only place files you intend to send inside it.

Troubleshooting

• connect failed … on serve — the daemon is not paired. Open http://127.0.0.1:8765/pair in a browser and scan the QR. Alternatively, run ./bin/whatsapp-mcp login in a terminal.
• another whatsapp-mcp instance is already running — only one serve can hold the store lock. Check for a stray process (ps aux | grep whatsapp-mcp) or another MCP client pointed at the same -store directory.
• QR doesn't display — the terminal doesn't render half-block Unicode. Try iTerm2, Windows Terminal, or similar.
• Device limit reached — WhatsApp caps linked devices. Remove one from Settings → Linked Devices on your phone.
• No messages loading — after initial auth, it can take several minutes for history to backfill. Use request_sync to target a specific chat.
• WhatsApp out of sync — delete both database files (store/messages.db and store/whatsapp.db) and re-run login.
• ffmpeg not found — send_audio_message needs ffmpeg on PATH to convert non-Opus audio. Use send_file for raw audio instead.

Debug logging

By default, JIDs in stderr logs are redacted to …<last-4-chars-of-user-part> and message bodies are summarised as [<length>B: text|url|command]. Media CDN URLs are collapsed to <scheme>://<host>/…. To see message content while actively debugging:

• As a flag: ./bin/whatsapp-mcp -debug serve

• As an env var in your MCP client config:

  Copy

  "env": { "WHATSAPP_MCP_DEBUG": "1" }

Even with debug mode on, phone-number-shaped digit sequences in bodies and JIDs are partially masked — only the last 5 digits are visible (e.g. +15551234567 → ****34567). This means debug logs are safe to share in bug reports without leaking full phone numbers.

Honesty disclaimer. The partial-redaction scheme is obfuscation for log-reader convenience, not anonymisation. Someone with independent knowledge of your contacts can still correlate the last 5 digits with a specific phone number. Treat redacted logs as "probably safe to paste into a GitHub issue", not "anonymised".

For Claude Desktop integration issues, see the MCP documentation.

Licence

MIT Licence — see LICENSE.