Training Sandbox

Practice x402 for Free

Full x402 environment on Base Sepolia testnet. Fake USDC, 5 test services, earn badges. No real money needed.

Testnet Configuration

Network

Base Sepolia (Chain ID: 84532)

USDC Contract

0x036CbD53842c5426634e7929541eC2318f3dCF7e

Sandbox Proxy

/api/v1/sandbox/proxy/[slug]

Get Testnet ETH

Coinbase Faucet

5 Test Services

Each service tests a different aspect of the x402 protocol. Complete them all to earn badges.

Echo Service

/sandbox-echo

$0.001 USDC

Basic x402 flow — send data, get it back

Tests: Payment flow, header signing, response parsing

Weather Service

/sandbox-weather

$0.002 USDC

Schema validation — typed input/output

Tests: Input schema, output parsing, content types

Session Service

/sandbox-session

$0.01 USDC

Session passes — pay once, call many

Tests: Session token purchase, reuse, expiry handling

Slow Service

/sandbox-slow

$0.001 USDC

Timeout handling — 2-5 second responses

Tests: Timeout configuration, retry logic, patience

Error Service

/sandbox-error

$0.001 USDC

Error handling — random 4xx/5xx responses

Tests: Error parsing, refund detection, graceful fallback

Quick Start

Test the sandbox echo service right now:

bash

# 1. Call without payment → get 402
curl https://402bazaar.com/api/v1/sandbox/proxy/sandbox-echo

# 2. Sign testnet USDC and call with payment
curl https://402bazaar.com/api/v1/sandbox/proxy/sandbox-echo \
  -H "X-PAYMENT: <your-signed-payment>"

# → 200 OK + echo response + badge earned!

Sandbox Badges

Earn badges by completing sandbox challenges. Badges display on your mainnet profile. Connect your wallet to track progress.

First 402

Received your first 402 Payment Required response

First Payment

Completed your first x402 payment

Weather Check

Called the sandbox-weather service with schema validation

Session Master

Purchased and used a session pass

Timeout Handler

Handled a slow response from sandbox-slow

Error Handler

Gracefully handled errors from sandbox-error

Interactive Playground

Test the x402 flow in your browser. Connect your wallet, pick a test service, and see the payment flow in real-time.

Open Playground