An x402 merchant that sells a real-world good: airtime in 150+ countries for USDC

General
1

Almost everything you can buy over x402 today is another API response. I built one that
delivers a physical-world good instead: mobile airtime and data top-ups in 150+ countries,
paid per order in USDC on Algorand, settled through the GoPlausible facilitator.

The interesting problem turned out not to be the payment. It is that an agent cannot take a
merchant to court. It gets one shot, cannot read a terms page, and cannot tell a good
merchant from a bad one. So the design is about making the promises checkable rather than
trusted:

  • the payment settles on chain before anything is bought;
  • a delivery that fails is refunded on chain automatically, from a separate wallet under a
    daily cap enforced in code;
  • every finished order carries an ed25519-signed receipt naming both transactions,
    verifiable offline against a published key — nothing in that check requires trusting me;
  • the delivery ledger is public, including the number that makes me look worst: stranded,
    meaning payers who were charged, received nothing, and whose refund also failed.

There is also a hosted MCP endpoint that holds no key of yours, and a Claude Code plugin and
an OpenClaw skill. The integration page below documents all three:

https://iomarkets.app/agent.md

The public delivery record:

https://iomarkets.app/v1/ledger

Built for the Global x402 Challenge. Happy to answer anything about the settlement design —
the refund and receipt paths are the parts I would most like torn apart.

2

This is an interesting real-world use case. For someone using a mobile wallet, what would the actual checkout experience look like—from sending USDC to receiving the airtime? Keeping that flow simple seems important for wider adoption.