Sending Bulk WhatsApp Messages via the API: A Developer Guide

If you’re a developer, you can send bulk WhatsApp via API in 2 ways: straight through Meta’s official WhatsApp Cloud API, or through a platform’s own REST API. Both get the job done. The trade-off is control versus setup time.

Two ways to send bulk WhatsApp via API

• Meta’s WhatsApp Cloud API directly: full control, but more setup and maintenance lands on you.
• A platform’s REST API (like WaMark): the platform handles infrastructure, templates, contacts and analytics; you call a simpler endpoint. Faster to ship.

How the Cloud API works

To send a template message, you make a POST request to the Cloud API’s messages endpoint for your phone number ID, authenticated with an access token. The JSON payload specifies the recipient, the approved template name, the language, and any variables.

For bulk, you loop over your recipient list and send individual template messages, respecting rate limits and your messaging tier. Webhooks tell you when each message is delivered, read or replied to.

Key things to handle

• Approved templates: marketing messages must use a pre-approved template.
• Opt-in: only message contacts who consented.
• Rate limits and tiers: your messaging limit depends on your quality rating and tier, so ramp volume gradually.
• Webhooks: capture delivered, read and reply events for tracking.
• Retries and errors: handle failures and back off cleanly.

Why many teams use a platform API instead

Building directly on the Cloud API means managing templates, contacts, rate limiting, webhooks and storage yourself. A platform’s REST API and webhooks handle most of that, so you send bulk messages with far less code. WaMark exposes a REST API and webhooks for exactly this.

For the non-technical overview, see our plain-English API explainer and the complete bulk messages guide. To build on WaMark, get started or explore the features.

Frequently asked questions

How do I send bulk WhatsApp messages via API?

Use the official WhatsApp Cloud API (or a platform’s REST API): authenticate, send approved template messages to each opted-in recipient, respect rate limits, and capture delivery webhooks.

Do I need approved templates to send via API?

Yes. To start conversations, including marketing, you must use Meta-approved templates. Replies within the 24-hour window can be free-form.

Should I build on the Cloud API or use a platform?

A platform’s API saves you managing templates, contacts, rate limits and webhooks yourself, so most teams ship faster that way.