{"id":565,"date":"2026-10-28T16:08:26","date_gmt":"2026-10-28T16:08:26","guid":{"rendered":"https:\/\/vectalk.com.br\/blog\/whatsapp-api-for-agencies\/"},"modified":"2026-10-28T16:08:30","modified_gmt":"2026-10-28T16:08:30","slug":"whatsapp-api-for-agencies","status":"publish","type":"post","link":"https:\/\/vectalk.com.br\/blog\/en\/whatsapp-api-for-agencies\/","title":{"rendered":"WhatsApp Business API for agencies: how to manage WhatsApp for multiple clients"},"content":{"rendered":"\n

Updated on October 28, 2026<\/em><\/p>\n\n\n\n

For an agency, the safest way to manage the WhatsApp Business API for multiple clients is to keep each client in their own Meta business portfolio, with their own WhatsApp account and messaging account, and give the agency partner access. That way messaging limits, quality, templates and billing stay separate per client, and the phone number still belongs to the client if the contract ends. On the technical side, the agency runs a single integration and tells clients apart by phone_number_id<\/code>.<\/p>\n\n\n\n

Below: structure, access, billing, templates, webhooks and per-client reporting.<\/p>\n\n\n\n

One portfolio per client: why not put everything together<\/h2>\n\n\n\n

Hanging every client’s number off the agency’s own portfolio looks simpler, but several Meta rules are calculated per portfolio or per account, which mixes one client’s risk with everyone else’s.<\/p>\n\n\n\n

Item<\/th>Where it lives in Meta<\/th>What happens if all clients share it<\/th><\/tr><\/thead>
Messaging limit (unique recipients outside the service window in 24 h)<\/td>Business portfolio<\/td>All numbers share one limit; one client’s campaign eats the others’ capacity<\/td><\/tr>
Business verification<\/td>Business portfolio<\/td>Verification belongs to the company that owns the portfolio, not to each client<\/td><\/tr>
Templates<\/td>Messaging account<\/td>Different clients’ templates sit in one list with one quality history<\/td><\/tr>
Payment method<\/td>Messaging account<\/td>One invoice the agency has to split<\/td><\/tr>
Policy enforcement restrictions<\/td>Messaging account<\/td>One client’s bad campaign can block sending for the rest<\/td><\/tr>
Display name<\/td>Phone number<\/td>Must represent the client’s business, not the agency<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Meta’s messaging limits documentation<\/a> is explicit: the limit applies to the portfolio, and every number in it shares the same quota. A new portfolio starts at 250 unique recipients per 24 hours and scales to 2,000, 10,000, 100,000 and unlimited. With separate clients, each one climbs its own ladder and keeps its own reputation. And if the client switches agencies, the number goes with them, with no dispute.<\/p>\n\n\n\n

The new account structure: WhatsApp account and messaging account<\/h2>\n\n\n\n

Since September 23, 2026, the old WABA has been split in two. The WhatsApp account<\/strong> holds the phone number. The messaging account<\/strong> holds templates, billing and webhooks. For an agency, the practical consequence is that access and vendor changes go through the WhatsApp account: switching providers means sharing the client’s WhatsApp account with the new partner. We cover the change in WhatsApp account vs messaging account<\/a>.<\/p>\n\n\n\n

How the agency gets access to client assets<\/h2>\n\n\n\n

There are two common paths, and many agencies use both.<\/p>\n\n\n\n

1. Embedded Signup<\/h3>\n\n\n\n

Embedded Signup is Meta’s flow, launched from a website or portal, in which the client logs in, picks or creates the portfolio, registers the number and authorizes the app to access those assets. Meta’s partner documentation<\/a> describes variants for clients who already use the WhatsApp Business app (coexistence) and for accounts created and shared through Meta Business Suite.<\/p>\n\n\n\n

In practice, the portfolio owner completes the screens themselves on a short call with the agency, without sharing any password.<\/p>\n\n\n\n

2. Partner access to the portfolio<\/h3>\n\n\n\n

For tasks done in Meta’s interface (WhatsApp Manager, templates, payments, verification), the client can grant the agency’s portfolio access to specific assets as a partner. The steps are in Meta’s Help Center: Give a partner access to assets in your business portfolio<\/a>.<\/p>\n\n\n\n

Ask only for the assets the agency needs, assign access to named people (never a shared login), and state in the contract that the client is always the portfolio admin.<\/p>\n\n\n\n

Who verifies the business<\/h3>\n\n\n\n

Business verification happens in the client’s portfolio, with the client’s documents. It is one of the paths to raise the limit from 250 to 2,000. According to the limits page, Meta also lets the partner that onboarded the client verify the business on the client’s behalf. Agree on who handles it.<\/p>\n\n\n\n

Who pays Meta: three billing models<\/h2>\n\n\n\n

Meta charges per delivered message, based on the message category and the recipient’s country. There are three common models:<\/p>\n\n\n\n

Model<\/th>Who pays Meta<\/th>How the agency bills the client<\/th><\/tr><\/thead>
Client with their own payment method<\/td>The client, directly on the messaging account<\/td>Agency bills only its own services<\/td><\/tr>
Provider with a credit line<\/td>The provider, which invoices the client<\/td>Agency bills its services; the provider invoices usage<\/td><\/tr>
Managed proxy (like Vectalk)<\/td>Vectalk pays Meta<\/td>Monthly fee plus prepaid balance at Vectalk; each delivered message is deducted from the balance; the agency decides whether to pass it on<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

The partner documentation explains that with Tech Providers, the client adds their own payment method and Meta bills them directly for usage, while Solution Partners can extend a credit line and invoice the client. The partner types are explained in what a BSP and a Tech Provider are<\/a>.<\/p>\n\n\n\n

If your clients message people in Brazil, these are Meta’s official rates in Brazilian reais (BRL) since October 1, 2026:<\/p>\n\n\n\n

Category<\/th>Meta rate (Brazil)<\/th><\/tr><\/thead>
Marketing<\/td>R$ 0.3217 per delivered message<\/td><\/tr>
Utility<\/td>R$ 0.0350<\/td><\/tr>
Authentication<\/td>R$ 0.0350<\/td><\/tr>
Service<\/td>R$ 0.0350, after the free tier of 1,000 per month per number<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

For other countries, use the rate cards on Meta’s pricing page<\/a>. Since October 2026, utility templates sent inside the customer service window are also charged. Explain this to the client before the first invoice. The article on utility messages inside the service window<\/a> has the details.<\/p>\n\n\n\n

Templates per client<\/h2>\n\n\n\n

Templates live in each client’s messaging account. That is a good thing: a rejected or paused template does not affect other clients. The agency’s job is to keep a standard so it doesn’t get lost across dozens of accounts.<\/p>\n\n\n\n

A naming convention that works:<\/p>\n\n\n\n

Part of the name<\/th>Example<\/th>Purpose<\/th><\/tr><\/thead>
Purpose<\/td>order_confirmed<\/code><\/td>Know what the template does<\/td><\/tr>
Variant<\/td>_v2<\/code><\/td>Change the copy without deleting history<\/td><\/tr>
Language (in the language<\/code> field)<\/td>en_US<\/code><\/td>Keep language versions under the same name<\/td><\/tr><\/tbody><\/table><\/figure>\n\n\n\n

Keep a library of approved copy by industry. The template examples by industry<\/a> are a good starting point. Before creating, check the category: promotional content is marketing, even if it looks like a notice. The guide on how Meta categorizes your template<\/a> explains the criteria.<\/p>\n\n\n\n

On Vectalk, creating a template uses the client’s instance token, and the messaging account is resolved from the token:<\/p>\n\n\n\n

curl -X POST https:\/\/apis.vectalk.com.br\/api\/templates \\\n  -H \"Authorization: Bearer CLIENT_A_INSTANCE_TOKEN\" \\\n  -H \"Content-Type: application\/json\" \\\n  -d '{\n    \"name\": \"order_confirmed_v2\",\n    \"language\": \"en_US\",\n    \"category\": \"UTILITY\",\n    \"components\": [\n      { \"type\": \"BODY\", \"text\": \"Hi {{1}}, your order #{{2}} has been confirmed.\",\n        \"example\": { \"body_text\": [[\"Anna\", \"4821\"]] } }\n    ]\n  }'<\/code><\/pre>\n\n\n\n
Webhooks and routing: one integration, many clients<\/h2>\n\n\n\n
Every Cloud API event arrives with the phone_number_id<\/code> in entry[].changes[].value.metadata<\/code>. That is how the agency knows which client a message belongs to. A minimal Node.js router, with the client map in code (in production, in your database):<\/p>\n\n\n\n
const CLIENTS = {\n  '1098765432': { name: 'sample-clinic', target: 'https:\/\/crm.agency.com\/clinic' },\n  '2034567891': { name: 'sample-store', target: 'https:\/\/crm.agency.com\/store' },\n};\n\nexport async function route(event) {\n  for (const entry of event.entry ?? []) {\n    for (const change of entry.changes ?? []) {\n      const id = change.value?.metadata?.phone_number_id;\n      const client = CLIENTS[id];\n      if (!client) {\n        console.warn('phone_number_id without client', id);\n        continue;\n      }\n      await fetch(client.target, {\n        method: 'POST',\n        headers: { 'Content-Type': 'application\/json' },\n        body: JSON.stringify(change.value),\n      });\n    }\n  }\n}<\/code><\/pre>\n\n\n\n
If you integrate directly with Meta, validate the X-Hub-Signature-256<\/code> signature before routing; see how to validate the webhook signature<\/a>.<\/p>\n\n\n\n
On Vectalk, you register several URLs per instance with POST \/api\/webhooks<\/code> (for example, the client’s CRM and the agency’s monitoring), and all of them receive the same event.<\/p>\n\n\n\n
Per-client reporting<\/h2>\n\n\n\n
Break it down by client and by month: messages sent, delivered, read and failed; sends by category (which drives cost); recurring errors, such as marketing opt-outs; and response time, if the agency runs customer service. Estimated cost is delivered messages per category times the rate. For service metrics, see WhatsApp customer service metrics<\/a>.<\/p>\n\n\n\n
On Vectalk, GET \/api\/messages<\/code> accepts date, status and direction filters. With an instance token, the query is already scoped to that client:<\/p>\n\n\n\n
curl \"https:\/\/apis.vectalk.com.br\/api\/messages?from=2026-10-01&to=2026-10-31&status=failed&direction=outbound\" \\\n  -H \"Authorization: Bearer CLIENT_A_INSTANCE_TOKEN\"<\/code><\/pre>\n\n\n\n
New client onboarding checklist<\/h2>\n\n\n\n
    \n
  1. Client’s own portfolio, with the client as admin, and verification started.<\/li>\n\n\n
  2. Number chosen (new or in coexistence) and a display name with the client’s brand.<\/li>\n\n\n
  3. Billing in writing: who pays Meta and how usage is passed on.<\/li>\n\n\n
  4. Contact opt-in documented by the client.<\/li>\n\n\n
  5. Approved templates, a webhook tested with a real message, and an agreed monthly report.<\/li>\n\n<\/ol>\n\n\n\n
    How to do it with Vectalk<\/h2>\n\n\n\n
    Vectalk is a proxy for Meta’s official WhatsApp Cloud API: payloads and webhooks are Meta’s, and the client pays Vectalk, which pays Meta. For agencies, three features cover most of the work:<\/p>\n\n\n\n