Test a payment

Test the whole payment path of Step 1, Payments, in the sandbox. Then continue to Step 2. The examples use http://localhost:3000/api/widgets as the protected endpoint.

Step 1: Confirm the challenge

Start your server. Call the paid endpoint without a payment.

curl -i http://localhost:3000/api/widgets
# HTTP/1.1 402 Payment Required
# PAYMENT-REQUIRED: <base64 JSON>

curl -i http://localhost:3000/api/widgets
# HTTP/1.1 402 Payment Required
# WWW-Authenticate: Payment id="…", realm="…", method="inflow", intent="charge", request="…"

An endpoint without a price must return 200.

curl -i http://localhost:3000/free

Result	Meaning
`402` with the correct header	The middleware works.
`200` on a paid endpoint	The middleware did not run for this endpoint.
An error at server start	Check the key, the environment, and the account type. See Errors.

Step 2: Read the challenge with the CLI

The CLI reads the challenge. It does not pay.

inflow x402 inspect http://localhost:3000/api/widgets

inflow mpp inspect http://localhost:3000/api/widgets

Confirm the price, the currency, and the payment options. To read a raw header, use inflow x402 decode or inflow mpp decode.

Step 3: Pay with the CLI

The CLI uses production by default. Your server runs in the sandbox, so add --sandbox to each command.

Install the CLI and unlock the vault

See Install the CLI. Run inflow vault unlock yourself, in your own terminal.

inflow auth login --sandbox --client-name "seller-test" --interval 5

Open the verification URL in your browser. Approve the login.

Check the sandbox balance

inflow balances list --sandbox

Pay the endpoint

inflow x402 pay http://localhost:3000/api/widgets --sandbox --interval 5

inflow mpp pay http://localhost:3000/api/widgets --sandbox --interval 5

Approve the payment when the CLI asks. The result contains the response body from your endpoint.

To use an API key instead, set INFLOW_API_KEY to a sandbox key. Keep --sandbox on each command. See Authenticate.

Step 4: Pay with a buyer example

Run a buyer example from the inflow-node repository. The MPP buyer example works only with the sandbox. It accepts a key from a sandbox Developer account or a sandbox Seller account.

MPP
x402

Start mpp-seller-express or mpp-seller-hono, or your own MPP server. Then run the buyer in a second terminal.

cd examples/mpp-buyer-fetch
cp .env.example .env
# fill in INFLOW_API_KEY from https://sandbox.inflowpay.ai
pnpm install
pnpm start

The default target is http://localhost:3000/api/widgets. To change it, set TARGET_URL in .env.A successful payment prints this output.

GET http://localhost:3000/api/widgets
  status: 200
  body: {"widgets":[1,2,3]}
  paid via inflow: 86f75793-abeb-4fe6-9a46-61901be77070

mpp-buyer-fetch replaces the global fetch with a payment-aware wrapper. For the explicit path, read mpp-buyer-manual.

Start your x402 server. Then run the buyer from the examples folder.

cd examples/x402-buyer-fetch
INFLOW_API_KEY=$INFLOW_API_KEY TARGET_URL=http://localhost:3000/api/widgets pnpm start

Other x402 buyer examples are x402-buyer-axios, x402-buyer-x402-evm, and x402-buyer-x402-svm.

Step 5: Check the result

The pay command returns status 200 and the real body from your endpoint.
The payment appears in the sandbox dashboard.
The amount matches your price.

Troubleshooting

The CLI reports an authentication error in the sandbox

Tokens stay in the environment that issued them. Log in again with --sandbox.

The pay command finds no option it can pay

Run inflow mpp supported --sandbox or inflow x402 supported --sandbox. Compare the result with the inspect output from step 2.

Every request returns 402, even after payment

The buyer and the server use different protocols. An MPP buyer cannot pay an x402 endpoint. Run inflow inspect on the endpoint first.

For server errors such as 403 SELLER_ACCOUNT_REQUIRED, see Errors.

Next step

Step 2: Enable agent enrollment

Let agents enroll with your service and get credentials.

Overview

Pay as an agent

Integrate your service

Concepts

Reference

Test a payment

Step 1: Confirm the challenge

Step 2: Read the challenge with the CLI

Step 3: Pay with the CLI

Step 4: Pay with a buyer example

Step 5: Check the result

Troubleshooting

Next step

Step 2: Enable agent enrollment

​Step 1: Confirm the challenge

​Step 2: Read the challenge with the CLI

​Step 3: Pay with the CLI

​Step 4: Pay with a buyer example

​Step 5: Check the result

​Troubleshooting

​Next step

Step 2: Enable agent enrollment

Step 1: Confirm the challenge

Step 2: Read the challenge with the CLI

Step 3: Pay with the CLI

Step 4: Pay with a buyer example

Step 5: Check the result

Troubleshooting

Next step