Sending the same WhatsApp message to hundreds or thousands of contacts can be done three ways: with the WhatsApp Business app, with unofficial tools, or with the official WhatsApp Business API. Only one of the three scales without putting your number at risk. This guide covers all three, what the official route costs, and how to launch your first campaign with Zavu's Broadcasts API, including the Meta rules that keep you from getting banned.
The three ways to send bulk WhatsApp messages
Broadcast lists in the WhatsApp Business app. Free and available from your phone, with two hard limits: each list caps at 256 contacts, and the message only reaches people who have your number saved in their address book. Enough for a small business with a fixed clientele. For marketing at scale, it does not exist.
Unofficial tools. Apps and browser extensions that automate regular WhatsApp or WhatsApp Business by pretending to be a human. They violate Meta's terms of service, and Meta bans numbers for that behavior every day. Everything you build on a banned number disappears with the number. Not a serious option for a business.
The official WhatsApp Business API. The channel Meta built for exactly this: outbound messages at any volume using pre-approved templates, sent to recipients who opted in. No 256-contact cap, no need to be in anyone's address book, and delivery is measurable message by message. It is the route Zavu uses and the only one we recommend. Starting from zero, our complete WhatsApp API guide covers getting connected in minutes.
The Meta rules to know before you send
Approved templates. To start a conversation (and a bulk campaign always starts conversations), the message must be a template Meta approved beforehand. Approval takes anywhere from minutes to 24 to 48 hours. Templates support variables, buttons, and media; our WhatsApp integration guide covers building them.
Opt-in. Meta's policy requires that recipients agreed to hear from your business. A checkout checkbox, a form, a prior conversation. Sending to purchased lists is the fastest way to destroy your number's quality rating.
Tiered messaging limits. A new number can start conversations with up to 250 unique customers per day. That limit rises automatically to 1,000, 10,000, 100,000, and then unlimited as you send with good quality. It is not paperwork, it is behavior: steady volume and few complaints raise the tier on their own.
Quality rating. Meta assigns your number a quality score based on blocks and reports from recipients. If it drops, your limits drop and templates can get paused. Quality is maintained with relevance, reasonable frequency, and an easy opt-out.
What it costs
Meta charges template messages per delivered message, with rates that vary by category (marketing, utility, or authentication) and by the recipient's country. Replies inside the 24-hour service window are free from Meta. Zavu passes Meta's rates through without adding a per-conversation fee; the per-category and per-country breakdown is in how WhatsApp's per-message pricing works and on the pricing page.
Step by step: your first campaign with the Broadcasts API
The flow is three calls: create the broadcast, load the contacts, send it. Before the first campaign you need an account with identity and business verification completed (KYC and KYB); it is required for every bulk send on Zavu, and drafts can be created and edited without it.
First, create the broadcast pointing at an approved template:
bashcurl -X POST https://api.zavu.dev/v1/broadcasts \ -H "Authorization: Bearer YOUR_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "name": "August launch", "channel": "whatsapp", "messageType": "template", "content": { "templateId": "tmpl_abc123" } }'
Then add contacts, up to 1,000 per request, with per-contact template variables:
bashcurl -X POST https://api.zavu.dev/v1/broadcasts/brd_abc123/contacts \ -H "Authorization: Bearer YOUR_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "contacts": [ { "recipient": "+5215512345678", "templateVariables": { "1": "Ana" } }, { "recipient": "+5491112345678", "templateVariables": { "1": "Bruno" } } ] }'
The response tells you how many were added, how many were duplicates, and which were invalid, so list cleaning happens before you spend a cent. Finally, send, immediately or scheduled:
bashcurl -X POST https://api.zavu.dev/v1/broadcasts/brd_abc123/send \ -H "Authorization: Bearer YOUR_API_KEY" \ -H "Content-Type: application/json" \ -d '{ "scheduledAt": "2026-08-15T14:00:00Z" }'
A WhatsApp broadcast built on a Meta-approved template starts sending directly, because the content already passed Meta's review. From there you can track progress in real time, with delivered and failed counts per contact, from the dashboard or the API. All of this also works without code from the Zavu dashboard, and the same API covers bulk SMS for recipients without WhatsApp.
How to not get banned: the short list
The number one cause of bans is messaging people who did not ask for it. Purchased list, guaranteed ban. Second is frequency: WhatsApp is an intimate channel and two campaigns a week already reads as spam to most audiences. Third is ignoring the signals: if a campaign generates blocks, the next one will generate more unless something changes. Segment, lower the frequency, and give every message a clear opt-out. Do that and the sending tiers climb on their own, and the number gains capacity instead of losing it.
Frequently asked questions
Is sending bulk WhatsApp messages legal? Yes, through the official API, with approved templates and recipient opt-in. Unofficial tools violate Meta's terms and risk the number, and depending on your country, unsolicited spam can also violate data protection law.
How many messages can I send per day? It depends on your number's tier: 250 new conversations per day at the start, rising automatically to 1,000, 10,000, 100,000, and unlimited based on volume and quality.
Can I do it without the API? Up to 256 contacts who have you saved, yes, with the app's broadcast lists. Beyond that, there is no official path without the API.
What about contacts who do not have WhatsApp? With Zavu you can run the same campaign over SMS as a fallback, from the same platform. Details in the bulk SMS guide.
Related resources
- How WhatsApp's per-message pricing works
- Complete WhatsApp API guide
- How to send bulk SMS
- Zavu's WhatsApp API
- WhatsApp API pricing
- How to build a WhatsApp chatbot
Conclusion
Bulk WhatsApp messaging works when it runs through the channel Meta built for it: approved templates, real opt-in, and an API that reports every delivery. The app tops out at 256 contacts, and unofficial tools cost you the number. With Zavu's Broadcasts API the first campaign is three calls, progress is visible live, and the same platform covers SMS fallback. Start with a list that said yes, a template worth receiving, and a frequency you would tolerate yourself.