Testing

In sandbox, the phone number, email or account number you send decides the outcome. Nothing reaches M-PESA, Airtel or a bank.

Rules

Use your sandbox keys. See Environments.
Use a new externalReference for every new transaction. A reused one returns 409 DUPLICATE_EXTERNAL_REFERENCE.
Test the failure path as carefully as the success path.
Confirm outcomes the same way you will in production: by webhook, or with Get transaction.
Need a webhook on demand? Call Simulate webhook with the transaction’s externalReference.

Create a sandbox checkout session, open the link, and enter these values on the hosted page.

Method	Value	Result
Mobile money	`254712345678`	Successful
Mobile money	`254787654321`	Failed
Mobile money	`25477777777`	Redirect, then successful
Mobile money	`25455555555`	Asks for an OTP
Bank transfer	`success@mail.com`	Returns a sandbox account, then successful
Bank transfer	`failure@mail.com`	Failed

Phone number	Result
`254712345678`	Successful
`254787654321`	Failed

`email`	Result
`success@mail.com`	Returns a sandbox account, then successful
`failure@mail.com`	Failed

Account names can be anything in sandbox.