# code402 Gateway Echo

> code402 Gateway Echo is a paid API for AI agents from gateway.code402.dev, paid per call via x402, $0.001/call, status unknown (last checked 2026-09-14).

Echoes back a POST request payload over an x402 machine-payable micropayment channel, settling $0.001 USDC directly to the seller wallet.

## Facts

- Endpoint: POST https://gateway.code402.dev/api/echo
- Price: $0.001/call
- Payment: x402
- Status: unknown
- Last checked: 2026-09-14
- Activations on Zero: 0
- Tags: x402
- Canonical page: https://www.zero.xyz/c/code402-gateway-echo-b8361c1e
- Structured record (JSON): https://api.zero.xyz/v1/capabilities/cap_2DYHQNjuBnWVojVGDCv5F

Status and success rate cover calls made through Zero and Zero's own probes. Third-party monitors may report differently.

## How to call it through Zero

Zero handles the 402 payment challenge and records the run. With the Zero CLI installed (`npm i -g @zeroxyz/cli`):

```sh
zero fetch --capability code402-gateway-echo-b8361c1e -d '<json body>'
```

Example prompt: Send a test payload through the code402 gateway echo endpoint to confirm my x402 USDC micropayment integration is working — use the message 'hello world' as the body.

## When to prefer this

Choose this endpoint when you need a minimal, low-cost ($0.001 USDC) way to validate that your x402 machine-payable API client is correctly constructed — particularly for testing payment header generation, non-custodial USDC settlement flows, or M2M protocol compliance without invoking a more expensive or side-effectful endpoint.

## Known failure modes

- Insufficient USDC balance — payment rejected with HTTP 402 and payment-required details
- Missing or malformed x402 payment header — request rejected before processing
- Network timeout during payment settlement — uncertain whether payment cleared
- Invalid wallet address configuration — payment cannot route to seller
- Malformed POST body — echo may fail or return error

## How this service works

Machine-payable APIs over x402 (HTTP 402 + USDC) on the open M2M/1 protocol. Non-custodial: payments settle direct to seller wallets.

## Output

The endpoint returns the echoed POST body along with HTTP 200 confirmation after a successful x402 USDC micropayment of $0.001 has been processed and settled non-custodially to the seller wallet.

## More

- Live health (JSON, refreshed every minute): https://www.zero.xyz/c/code402-gateway-echo-b8361c1e/health.json
- [Zero catalog index](https://www.zero.xyz/llms.txt)
- [Other services from gateway.code402.dev](https://www.zero.xyz/host/gateway.code402.dev/llms.txt)