openclaw-kapso-whatsapp

Give your OpenClaw AI agent a WhatsApp number. Official Meta Cloud API via Kapso — a unified API for WhatsApp Cloud. No ban risk. Stateless. Two Go binaries. Near-zero idle CPU.

Architecture

WhatsApp --> Kapso API --> kapso-whatsapp-bridge --> OpenClaw Gateway --> AI Agent
   ^                                |
   +--------------------------------+
          relay: reads session JSONL, sends reply back

Libraries like Baileys and whatsapp-web.js reverse-engineer WhatsApp Web — Meta actively detects and bans these connections. This bridge uses the official Cloud API through Kapso, so your number stays safe. Stateless API calls, no session management, near-zero idle CPU.

Table of contents

Installation
Quick start
Configuration
Security
Delivery modes
Voice transcription
Development
Contributing

Installation

curl -fsSL https://raw.githubusercontent.com/Enriquefft/openclaw-kapso-whatsapp/main/scripts/install.sh | bash

Downloads the latest release, verifies SHA256 checksums, and installs to ~/.local/bin. Override the install directory or version:

INSTALL_DIR=/usr/local/bin TAG=v0.2.1 curl -fsSL https://raw.githubusercontent.com/Enriquefft/openclaw-kapso-whatsapp/main/scripts/install.sh | bash

NixOS / Home Manager

# flake.nix
inputs.kapso-whatsapp = {
  url = "github:Enriquefft/openclaw-kapso-whatsapp";
  inputs.nixpkgs.follows = "nixpkgs";
};

Then in your home-manager config:

imports = [ inputs.kapso-whatsapp.homeManagerModules.default ];

services.kapso-whatsapp = {
  enable = true;
  package = inputs.kapso-whatsapp.packages.${pkgs.system}.bridge;
  cliPackage = inputs.kapso-whatsapp.packages.${pkgs.system}.cli;
  secrets.apiKeyFile = config.sops.secrets.kapso-api-key.path;          # or any file path
  secrets.phoneNumberIdFile = config.sops.secrets.kapso-phone-number-id.path;
};

The module generates ~/.config/kapso-whatsapp/config.toml, installs the CLI, and creates a systemd user service. Secrets are read from files at startup — works with sops-nix, agenix, or plain files.

Quick start

No config file. No database. No reverse proxy.

export KAPSO_API_KEY="your-key"
export KAPSO_PHONE_NUMBER_ID="your-phone-number-id"

# Verify everything is configured correctly
kapso-whatsapp-cli preflight

# Start the bridge
kapso-whatsapp-bridge

That's it — polling mode works with zero configuration. To cut latency to under 1 second, see Tailscale Funnel mode.

Configuration

The Quick start covers the minimum: just two env vars. Everything else has sensible defaults.

Loading order: built-in defaults → config file → env vars. Environment variables always win.

Full config reference

Create ~/.config/kapso-whatsapp/config.toml (or set KAPSO_CONFIG to a custom path):

[kapso]
api_key = ""              # prefer KAPSO_API_KEY env var for secrets
phone_number_id = ""      # prefer KAPSO_PHONE_NUMBER_ID env var

[delivery]
mode = "polling"          # "polling" | "tailscale" | "domain"
poll_interval = 30        # seconds (minimum 5)
poll_fallback = false     # run polling alongside webhook as safety net

[webhook]
addr = ":18790"
verify_token = ""         # prefer KAPSO_WEBHOOK_VERIFY_TOKEN env var
secret = ""               # prefer KAPSO_WEBHOOK_SECRET env var

[gateway]
url = "ws://127.0.0.1:18789"
token = ""                # prefer OPENCLAW_TOKEN env var
session_key = "main"
sessions_json = "~/.openclaw/agents/main/sessions/sessions.json"

[state]
dir = "~/.config/kapso-whatsapp"

Variable	When needed
`KAPSO_API_KEY`	Always
`KAPSO_PHONE_NUMBER_ID`	Always
`KAPSO_WEBHOOK_VERIFY_TOKEN`	Tailscale or domain mode
`KAPSO_WEBHOOK_SECRET`	Domain mode (optional, HMAC validation)
`OPENCLAW_TOKEN`	If gateway auth is enabled

Security

The bridge enforces sender allowlisting, per-sender rate limiting, role tagging, and session isolation. By default, security mode is allowlist — only phone numbers listed in [security.roles] can interact with the agent.

Security configuration

[security]
mode = "allowlist"                    # "allowlist" | "open"
deny_message = "Sorry, you are not authorized to use this service."
rate_limit = 10                       # max messages per window per sender
rate_window = 60                      # window in seconds
session_isolation = true              # per-sender sessions (false = shared)
default_role = "member"               # role for unlisted senders in "open" mode

[security.roles]
admin = ["+1234567890"]
member = ["+0987654321", "+1122334455"]

Each role maps to a list of phone numbers. The agent receives a [role: <role>] tag in every forwarded message, enabling role-based capability enforcement in SKILL.md.

For simple setups without roles, use env vars:

Variable	Description
`KAPSO_SECURITY_MODE`	`"allowlist"` or `"open"`
`KAPSO_ALLOWED_NUMBERS`	Comma-separated phone numbers (all get `default_role`)
`KAPSO_DENY_MESSAGE`	Message sent to unauthorized senders
`KAPSO_RATE_LIMIT` / `KAPSO_RATE_WINDOW`	Rate limit settings
`KAPSO_SESSION_ISOLATION`	`"true"` or `"false"`

Behavior:

Allowlist mode (default): Only numbers in [security.roles] can send messages. Unauthorized senders receive the deny message.
Open mode: Anyone can send. Senders not in the roles map get default_role.
Rate limiting: Fixed-window token bucket per sender. Excess messages are silently dropped.
Session isolation (default on): Each sender gets their own OpenClaw session, preventing cross-sender context leakage.

Delivery modes

Polling (default)

Works out of the box — no public endpoint, no domain, no tunnel. Polls every 30 seconds.

Tailscale Funnel (zero-config tunnel)

Real-time delivery (< 1s latency) without owning a domain. The bridge starts Tailscale Funnel automatically. Works on the free plan.

[delivery]
mode = "tailscale"

Plus set KAPSO_WEBHOOK_VERIFY_TOKEN. Prerequisites: Tailscale installed and running.

Your own domain

Point your reverse proxy at the webhook server (:18790).

[delivery]
mode = "domain"

Plus set KAPSO_WEBHOOK_VERIFY_TOKEN (and optionally KAPSO_WEBHOOK_SECRET for HMAC validation). Register https://yourdomain.com/webhook in Kapso.

Polling fallback: Any webhook mode can also run polling as a safety net by setting poll_fallback = true. Messages are deduplicated by ID.

Voice transcription

Incoming voice notes are automatically transcribed and forwarded as [voice] <transcript>. If transcription is not configured or fails, the message is forwarded as [audio] (audio/ogg) instead. No messages are ever lost.

Transcription configuration

Cloud providers

[transcribe]
provider = "groq"           # "groq" | "openai" | "deepgram"
api_key = ""                # prefer KAPSO_TRANSCRIBE_API_KEY env var

Provider	Default model	Base URL
`groq`	`whisper-large-v3`	`api.groq.com/openai/v1`
`openai`	`whisper-1`	`api.openai.com/v1`
`deepgram`	`nova-3`	`api.deepgram.com/v1`

All cloud providers include automatic retry on 429/5xx (3 attempts, exponential backoff).

Local provider (whisper.cpp)

No API costs. Requires whisper.cpp and ffmpeg installed.

[transcribe]
provider = "local"
binary_path = "whisper-cli"          # path to whisper-cli binary
model_path = "/path/to/ggml-base.bin"

Full reference

[transcribe]
provider = ""               # "groq" | "openai" | "deepgram" | "local" (empty = disabled)
api_key = ""                # API key for cloud providers
model = ""                  # override default model per provider
language = ""               # language hint (empty = auto-detect)
max_audio_size = 26214400   # max download size in bytes (default 25MB)
binary_path = "whisper-cli" # local provider only
model_path = ""             # local provider only
timeout = 30                # per-call timeout in seconds (cloud providers)
no_speech_threshold = 0.85  # silence detection — above this, falls back to [audio]
cache_ttl = 3600            # transcript cache lifetime in seconds (SHA-256 keyed)
debug = false               # log avg_logprob, no_speech_prob, detected language

Minimal cloud setup with env vars only:

export KAPSO_TRANSCRIBE_PROVIDER="groq"
export KAPSO_TRANSCRIBE_API_KEY="your-key"

Development

Prerequisites

Go 1.22+
(Optional) just command runner

Building and testing

# From source
go install github.com/Enriquefft/openclaw-kapso-whatsapp/cmd/kapso-whatsapp-cli@latest
go install github.com/Enriquefft/openclaw-kapso-whatsapp/cmd/kapso-whatsapp-bridge@latest

# With just
just build          # Build both binaries
just test           # Run tests
just lint           # Run golangci-lint
just check          # Run tests + vet + format check

If you use Nix, direnv allow or nix develop gives you Go, gopls, golangci-lint, goreleaser, and just.

Project structure

cmd/
  kapso-whatsapp-cli/       CLI for sending messages and preflight checks
  kapso-whatsapp-bridge/    Receives inbound messages (polling, tailscale, or domain)
internal/
  config/                   TOML config loading with env var overrides
  kapso/                    Kapso API client, message types, list endpoint
  gateway/                  WebSocket client to OpenClaw gateway
  delivery/                 Source abstraction, fan-in merge, dedup, extraction
    poller/                 Polling source
    webhook/                HTTP webhook source
  relay/                    Relay agent replies back to WhatsApp
  security/                 Allowlist, rate limiting, role tagging, session isolation
  transcribe/               Voice transcription providers and caching
  preflight/                Setup verification checks
  tailscale/                Tailscale Funnel automation (auto-start, URL discovery)
scripts/
  install.sh                Curl-pipe-bash installer with checksum verification
nix/
  module.nix                Home-manager module with typed options + sops-nix support
skills/
  whatsapp/                 SKILL.md — agent instructions

Contributing

Issues and PRs welcome. Run just check before submitting.

License

MIT

Name		Name	Last commit message	Last commit date
Latest commit History 130 Commits
.github		.github
.planning		.planning
cmd		cmd
internal		internal
nix		nix
scripts		scripts
skills/whatsapp		skills/whatsapp
.envrc		.envrc
.gitignore		.gitignore
.goreleaser.yml		.goreleaser.yml
CHANGELOG.md		CHANGELOG.md
CLAUDE.md		CLAUDE.md
CONTRIBUTING.md		CONTRIBUTING.md
LICENSE		LICENSE
README.md		README.md
SECURITY.md		SECURITY.md
TODO.md		TODO.md
flake.lock		flake.lock
flake.nix		flake.nix
go.mod		go.mod
go.sum		go.sum
justfile		justfile

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openclaw-kapso-whatsapp

Architecture

Installation

Quick start

Configuration

Security

Delivery modes

Polling (default)

Tailscale Funnel (zero-config tunnel)

Your own domain

Voice transcription

Cloud providers

Local provider (whisper.cpp)

Full reference

Development

Prerequisites

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openclaw-kapso-whatsapp

Architecture

Installation

Quick start

Configuration

Security

Delivery modes

Polling (default)

Tailscale Funnel (zero-config tunnel)

Your own domain

Voice transcription

Cloud providers

Local provider (whisper.cpp)

Full reference

Development

Prerequisites

Building and testing

Project structure

Contributing

License

About

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