A Kapso alternative for linking a number you already use

Kapso describes itself as WhatsApp for developers, and it is one of the more developer-friendly ways onto the official WhatsApp Cloud API: a TypeScript SDK, a CLI, an MCP server, signed webhooks, workflows and AI agents, with a free plan to start. wuapi is aimed at the same developers from the other side of the platform, linking a number as a device instead of registering it. This page is about which side your product belongs on.

#What Kapso is

Kapso is an official partner of the WhatsApp Business Platform. Numbers are connected through the platform's embedded signup, either yours or a customer's through a setup link, and Kapso can also hand you a pre-verified US number from its own pool. There is a shared sandbox number for testing.

On top of the connection it gives you:

• An API that mirrors the Cloud API, proxied through api.kapso.ai, plus a platform API for its own features, all under one project key sent as X-API-Key.
• An open-source TypeScript SDK, @kapso/whatsapp-cloud-api, MIT licensed, which also works directly against the Cloud API.
• A CLI and an MCP server that can send messages, read conversations, and manage templates and webhooks.
• Webhooks signed with HMAC-SHA256 over the raw body in X-Webhook-Signature, retried immediately, then after 10 and 40 seconds, and paused automatically if an endpoint keeps failing.
• An inbox, workflows and AI agents with human handoff.

It also supports coexistence, the platform's option to keep a number in the WhatsApp Business app while the Cloud API uses it, and its docs are candid that this is less stable than a dedicated Cloud API connection.

#What it costs

From Kapso's pricing page, in US dollars. A message is anything sent or received, and read receipts do not count.

• Free is 2,000 messages a month on 1 connected number, with a sandbox number and function calls included.
• Pro is $25 a month for 100,000 messages and 3 numbers, then $0.002 per extra message and a monthly fee per extra number.
• Platform is $299 a month for 1,000,000 messages and 50 numbers, then $0.001 per extra message.
• Enterprise is priced on request.

WhatsApp's own template fees are separate. Kapso lets you pay them through it at cost or directly to the platform. Its docs, like the platform's own pricing pages, note that service replies inside the 24 hour window stop being free on October 1, 2026. Each business phone number keeps 1,000 free service messages a month, service messages get no volume tiers, and free entry point windows stay free.

#The two prices at two sizes

The platform prices are close enough that the model decides, not the invoice.

For three numbers, Kapso Pro is $25 a month with 100,000 messages included, plus WhatsApp's fee on every template and, from October 2026, on service replies too. Three linked numbers on wuapi are $15 a month: $6 for the first and $4.50 for each of the other two, with no count of messages and no fee from WhatsApp.

For fifty numbers, Kapso Platform is $299 a month with a million messages, plus the same WhatsApp fees. Fifty linked numbers on wuapi are $226.50 a month, and include 25 GB a month of residential proxy traffic, pooled; past that, traffic is $0.99 per GB.

So on the platform line, the two land near each other. The line that separates them is WhatsApp's per-message fee, which a product that mostly answers customers barely pays today and from October 2026 will pay on every reply past the first 1,000 a month per number, and which a linked number never pays. A product that mostly sends templates pays it either way, because it needs the official platform anyway.

#When Kapso is the right call

• Your product sends templates. Reminders, receipts and codes to people outside the 24 hour window need approved templates, and Kapso makes managing them pleasant.
• You onboard your customers' own business numbers. Setup links that walk a customer through the official signup are exactly the multi-tenant flow the official platform supports.
• You want verification and scale. A verified sender, the business badge and messaging tiers that grow with quality exist only on the official platform.
• You want hosted agents and workflows. If the product is mostly a bot with a handoff to a human, Kapso has those pieces built in.

For any of those, stay. Linked device or Cloud API has the full decision.

#When a linked number fits better

wuapi links a number the way WhatsApp Web links to a phone. Nothing is registered, so the number stays a normal account in the WhatsApp app, and your code sends and receives next to the person using it.

• Every chat, groups included. A linked device sees what the phone sees. It can create groups, add and remove participants, and post. Groups are among the things coexistence does not sync to the Cloud API.
• No templates and no window. Messages are normal messages at any time, to people who expect them.
• A price per number. $6 for the first, $4.50 each from the second to the fiftieth, $3.50 after, with no count of messages on a paid number.
• A Free plan of a similar size. 1 number, 2,000 messages a month counting sent and received, and 0.5 GB of proxy traffic. See pricing.

What you give up is what the official platform adds: templates, buttons and list messages, the verified badge and its scaling tiers. A linked number sends at a person's pace, and WhatsApp can restrict it for what it sends, the same as any account.

#What comes with a wuapi number

A residential exit. Each number connects through a residential proxy with a sticky exit in the country and city you choose. If the proxy fails, the number waits offline and never falls back to a datacenter IP. The exit is part of what keeps a linked number looking like the person it belongs to; the official platform has no equivalent because nothing is linked.

Pacing. A per-minute cap, a lower cap for first contacts and a typing indicator, per number and off by default, set with PATCH /v1/accounts/{accountId}. We recommend 12 a minute and 5 to new contacts for outbound sending. Keep your number healthy explains when.

Webhooks that wait for you. Kapso and wuapi both sign with HMAC-SHA256. wuapi signs the timestamp together with the body in Wuapi-Signature, so an old request cannot be replayed, and retries a failed delivery at 30s, 2m, 10m, 1h and 6h, which rides out a deploy or a short outage on your side.

Idempotent sends and projects. An Idempotency-Key on any POST is kept for 24 hours. Projects keep customers apart, each with its own numbers, keys, webhooks and usage.

An SDK and an MCP server. @wuapidev/sdk for TypeScript, an OpenAPI 3.1 file, and a local and hosted MCP server.

#Side by side

#Moving from Kapso

If part of your traffic is conversational and you want those numbers linked instead:

// Kapso, with its open-source SDK
await client.messages.sendText({
  phoneNumberId: PHONE_NUMBER_ID,
  to: "5511987654321",
  body: "Thanks, we have your booking.",
})

// wuapi
await wuapi.messages.send({ accountId, to: "+5511987654321", text: "Thanks, we have your booking." })

The steps that take time:

1. Choose the number. A number on the Cloud API has to be released from it before it can be linked as a device, so most teams link a separate number for the conversational side.
2. Keep templates where they are. Traffic that needs templates stays on the official platform. Running both is normal.
3. Update the webhook check to verify the timestamp too, as the docs show.

#Questions people ask