Skip the Meta setup
Use the Kapso sandbox number to start building before completing the full Meta setup for your own number.
WhatsApp API sandbox for developers
Send and receive real WhatsApp messages from your own phone in minutes. Build against the same API you will ship with, before you connect a production number.
Why start in the sandbox
Start building without having to complete the full Meta setup. Test your integration with a sandbox number, then connect your production number when you are ready.
Real WhatsApp, not a simulator
Messages travel through WhatsApp to the phone you register. You see exactly what your users will see, including buttons and lists.
The same API you will ship with
Sandbox WhatsApp is a regular WhatsApp configuration in your project. Endpoints, webhook payloads, agents, and Flows carry over unchanged when you connect your own number.
Included in every plan
Every Kapso project comes with sandbox access, including the Free plan. Sign up, add your phone, and start testing.
Three steps to your first message
Keep your phone nearby. You will send one WhatsApp message to activate the session.
-
Add your phone
Open WhatsApp → Sandbox, click Add session, and enter your phone number in international format.
-
Send the activation code
Tap Open WhatsApp with Code and send it from your registered phone. The code expires after 15 minutes.
-
Build and message it
Connect your agent, Flow, or code to Sandbox WhatsApp. Send a message from your phone to test it.
Plug it into whatever you are building
Every project gets a Sandbox WhatsApp configuration automatically. Select it anywhere you would select a production number.
AI agents
Choose Sandbox WhatsApp in your agent settings and save. Chat with the agent from your phone and tune its replies before customers ever see it.
Kapso Flows
Add an Inbound Message Trigger, select Sandbox WhatsApp, and deploy. Every message you send from your phone runs the workflow end to end.
Webhooks
Open Sandbox WhatsApp under WhatsApp → Configurations and choose Manage Webhooks. Receive message, status, and conversation events at your own URL.
Your own code
Call the same REST API, SDKs, CLI, and MCP server you will use in production. The only difference is the configuration you point them at.
Build in the sandbox, ship on your number
Same project, same code. Connect a production number when you are ready for customers.
Sandbox
- Messages to phones you register
- Text, buttons, and lists
- Included in every plan
Production
- Messages to any WhatsApp user
- Templates and broadcasts
- Your business name and number
Frequently asked questions
What is a WhatsApp API sandbox?
A sandbox is a test environment for the WhatsApp Business API. Kapso gives every project a shared sandbox number that is already live with Meta. You register your own phone, activate it with a code, and exchange real WhatsApp messages with your agent, Flow, or code before you connect a production number.
Is the Kapso WhatsApp sandbox free?
Yes. The sandbox is included in every Kapso plan, including Free, and signing up does not require a credit card.
Do I need a Meta Business account or a verified number to use it?
No. The sandbox number belongs to Kapso and is already verified. You only need a phone with WhatsApp to test from. Business verification and your own number come later, when you move to production.
What can I send from the sandbox?
Text and interactive messages, such as buttons and lists, to any phone with an active sandbox session. Template messages, template sync, and sending to many recipients at once need a production number.
How do I activate a session, and how long is the code valid?
Open WhatsApp → Sandbox in your project, click Add session, and enter your phone number. Send the six-character code to the sandbox number from that phone. Codes expire 15 minutes after the session is created, so create a new session if yours runs out.
Can I use the same phone in more than one project?
One project at a time. Create a session in the other project and activate it from the same phone. The earlier session becomes superseded, its open sandbox conversations close, and new messages route only to the active session.
Your first WhatsApp message is minutes away
Create a project, add your phone, send the code. Then build against the same API you will ship with.