High-volume WhatsApp messaging gateway

We built a REST gateway that runs many WhatsApp sessions in parallel for sending text, images and documents.

Sector: Communication. Platforms: API, Dashboard. Client: kept confidential.

The challenge

Internal systems needed to send large volumes of WhatsApp messages through several linked numbers, without manual handling and without losing sessions.

What we built

The gateway manages several linked sessions through a dashboard with QR-code linking, queues outgoing messages and pools resources between sessions.

A watchdog and a memory monitor recover unhealthy sessions, and load tests guided the capacity plan.

Key features

Multiple concurrent messaging sessions
QR-code linking dashboard
Message queue for text, images and documents
API key and dashboard authentication
Session watchdog and memory monitoring
Load-testing scripts

Engineering notes

We documented where serverless hosting fits and where a persistent virtual machine works better for long-lived connections.

Technology

Node.js
Express
Baileys
PM2