Whatsapp Embedded Signup

The problem

Integrating Meta's WhatsApp Embedded Signup is notoriously error-prone, involving complex JavaScript SDK handshakes, server-side OAuth exchanges, and specific Meta Business Manager configurations that often fail silently or return cryptic errors.

What it does

• Provides a complete implementation pattern for both Coexistence mode and standard Cloud API flows.
• Enables server-side HMAC-SHA256 verification for mandatory Meta compliance webhooks.
• Implements a generic webhook routing system to handle multi-tenant message delivery via phone_number_id.
• Configures the Next.js frontend to capture the specific window.postMessage events required for reliable onboarding.
• Solves specific PostgreSQL search_path bugs and multi-tenant session management issues during the connection lifecycle.

Frameworks & tools

FastAPI, Python, Next.js, React, Meta Graph API, PostgreSQL.

Why this beats prompting it yourself

Generic LLM prompts often miss the critical featureType parameters and Meta-specific event strings like FINISH_WHATSAPP_BUSINESS_APP_ONBOARDING that are poorly documented. This skill provides the battle-tested configuration values and backend routing logic needed to avoid the "JSSDK is disabled" and "code already used" errors that stall development.

Use cases

• Onboarding client WhatsApp Business Accounts directly from your SaaS dashboard.
• Enabling "Coexistence" so clients can use your platform and their mobile app simultaneously.
• Setting up required "Deauthorize" and "Data Deletion" endpoints for Meta App Review.
• Migrating clients from other BSPs (Twilio, MessageBird) to your own Tech Provider app.

Known limitations

Requires an approved Meta Tech Provider status and an app in production mode. Coexistence mode availability depends on the quality and history of the client's phone number.