Testing x402 Sandbox Endpoints (Base Testnet)

2026-04-06

The Node4All sandbox is built for real endpoint testing, not placeholder demos. You can validate the full x402 payment challenge flow against live test networks (starting with Base Sepolia), while still using test funds and a safe integration environment.

Download the Postman collection (WIP)

We published a downloadable Postman collection that includes our currently available sandbox endpoints.

Download JSON: node4all-x402.postman_collection.json
Import in Postman: In Postman, choose Import → Link, then paste: https://node4all.com/postman/node4all-x402.postman_collection.json

The collection is still WIP and will grow as additional services are released.

Sandbox endpoint overview (quick reference)

GET /v1/x402-test
Primary x402 v2 validation route on Base Sepolia. The subdomain implies the network — sandbox = Base Sepolia, api = Base Mainnet. No ?chain=…&network=… query params needed; the server advertises accepted networks in the base64-encoded PAYMENT-REQUIRED response header.
POST /v1/md2pdf
x402 v2 paid Markdown → PDF endpoint. Accepts JSON or multipart .md uploads (≤10MB) and returns application/pdf.
POST /v1/pdf2md
x402 v2 paid PDF → Markdown endpoint. Multipart .pdf upload (≤10MB), returns text/markdown for low-token agent ingestion.
Sandbox docs: https://sandbox.node4all.com/docs
Agent-readable discovery: https://sandbox.node4all.com/.well-known/x402.json and /llms.txt.

MCP + agent toolkit (early access)

We also publish @node4all/x402-agent-toolkit on npmjs. It includes an MCP server so AI agents can call available Node4All sandbox endpoints directly and complete x402 flows with a configured wallet.

This is the fastest path if you want an agent to:

discover and call the endpoint tools,
handle x402 payment challenges,
and execute requests with wallet-backed payment proofs.

What's next

A full blog post with complete step-by-step instructions (wallet setup, request/response flow, and troubleshooting) will follow shortly.