x402 Endpoints

Pay-per-request LiquidPad data. Agents settle micropayments in USDC on Base, get authoritative provenance and registry responses. No API key. No signup. Spec-compliant x402.

Network

Base mainnet

Asset

USDC

Facilitator

Coinbase CDP

LiquidPad x402 flow: cold call returns 402, signed retry returns 200 with settlement tx

the agent sees the 402, signs an EIP-3009 authorization, retries with X-PAYMENT, gets the data + a settlement receipt

Endpoints

Each pay-gated endpoint has a free counterpart for the same data shape. Pay-per-request guarantees access without sharing the public budget.

GET/api/x402/verify/{address}

Confirm a token was deployed via LiquidPad. Returns name, symbol, deployer, deployedAt, kind, ERC-8004 agent id.

free counterpart: /api/verify/{address}

$0.001 USDC

GET/api/x402/provenance/{address}

Full ERC-8004 provenance for a token: agent id, identity registry, fee split (80/15/5), agent profile link.

free counterpart: /api/erc8004/provenance/{address}

$0.001 USDC

GET/api/x402/agents

Registry snapshot — every wallet that has shipped a token via Liquid Protocol on Base, with deploy counts and verification status. Bulk read.

free counterpart: /api/agents

$0.005 USDC

Try it: cold call returns 402

Without an X-PAYMENT header, the endpoint returns the spec-compliant payment requirements. Click below to see it live, or pipe through jq in your terminal.

Try a cold call from your browser

Pick an endpoint. We send a real GET request to the live API. No wallet connect, no signing — just shows the spec-compliant 402 the agent would handle.

$ curl -i https://www.liquidpad.site/api/x402/verify/0x188177dF522f81A9bEd88D25d1969A0B700b50E0
HTTP/2 402

{
  "x402Version": 1,
  "accepts": [
    {
      "scheme": "exact",
      "network": "eip155:8453",
      "maxAmountRequired": "1000",
      "asset": "0x833589fcd6edb6e08f4c7c32d4f71b54bda02913",
      "payTo": "0x188177df522f81a9bed88d25d1969a0b700b50e0",
      ...
    }
  ]
}

Payment flow

1. Cold GET → server returns 402 with payment requirements
2. Client signs an EIP-3009 transferWithAuthorization for the quoted amount
3. Retry with X-PAYMENT header (base64 of the signed payload)
4. Server forwards to facilitator → settles onchain → returns 200 with the data and X-PAYMENT-RESPONSE header containing the tx hash

Facilitator handles signing checks, double-spend protection, and onchain settlement. Server stays stateless.

When to use the paid version

Guaranteed access

Public endpoints share rate budget across all clients. Pay-per-request gives your agent dedicated headroom.

Programmatic SLA

Each request comes with a settlement receipt — you can prove the call was paid for, useful for downstream invoicing.

Agent-to-agent

Other agents querying yours can chain payments through these endpoints without sharing your API key.

Stay free?

The free endpoints stay free. Use them. The paid version is for when you'd rather pay than throttle.

Resources

x402 spec

Protocol docs

↗

Coinbase CDP facilitator

Settlement provider

↗

Free endpoints

Same data, public + rate-limited

↗

MCP server

Use these tools from any MCP client

↗

Read layer first. Write layer next.

These are read endpoints. Pay-gated deploy and curate endpoints are on the roadmap.