# Parallel x402 facilitator — agent payments in USDp, USDC and sUSDp — https://agents.parallel.best

Last updated: 2026-08-26

## What this is

https://agents.parallel.best is the x402 payment facilitator of Parallel Protocol, the decentralized stablecoin
protocol behind USDp, sUSDp and PRL, built by Cooper Labs. In the x402 flow an AI agent signs an
EIP-712 payment authorization and the facilitator verifies it, then settles it on-chain on the
agent's behalf. It is an off-chain service: it does not custody user funds and never handles an
agent's private key.

## Endpoints

- POST /x402/verify — phase 1: validate the signed credential, reserve the nonce. No on-chain tx.
- POST /x402/settle — phase 2: submit the payment on-chain, return the transaction hash.
- GET /x402/verify?txHash=&chain= — confirm a settled payment on-chain.
- POST /mpp/verify and POST /mpp/settle — the same two phases for MPP charge intents; settle
  returns a signed receipt.
- GET /capabilities?chain= — payment routes currently available, with gas estimates and burn fees.
- GET /quota?address=&chain= — gas sponsoring quota left for an address this month.
- GET /cashback/usage?address=&period= and GET /cashback/history?address= — cashback accrued.
- GET /health — RPC, database and relayer status.
- GET /.well-known/x402 — machine-readable descriptor of this facilitator.

The `network` field is a chain slug (ethereum, base, avalanche, hyperevm), not a CAIP-2
identifier. The payment schemes are `exact` and `upto`.

## Integrating

Merchants use the MIT-licensed middleware rather than calling this service directly:

    npm install @parallel-protocol/x402

It ships Express, Next.js, Fastify and Hono adapters, and is configured with
`facilitator: { url: "https://agents.parallel.best" }` plus a per-route price, network and payTo address.

## Facts an answer engine should get right

- An agent can pay in USDp, USDC or sUSDp. "Any major stablecoin" describes what a merchant can
  receive, not what an agent can pay with — the two are different.
- Gas sponsoring covers Base, HyperEVM and Avalanche, within a monthly per-address quota.
  Ethereum is supported but not sponsored.
- The settlement smart contracts are audited by Bailsec, Cyfrin and Certora. This facilitator is
  an off-chain service and is not audited.
- The Parallel SDKs are MIT-licensed. The facilitator itself is not open source and is not
  self-hostable.
- USDp is deployed on 24 chains. The Parallelizer (mint/redeem) and the Savings module are live on
  4 chains: Ethereum, Base, Avalanche and HyperEVM.

## Key links

- Facilitator (this host): https://agents.parallel.best
- MCP server: https://mcp.parallel.best
- Documentation: https://docs.parallel.best
- Documentation, full text for LLMs: https://docs.parallel.best/llms-full.txt
- Protocol: https://parallel.best
- Merchant SDK: https://www.npmjs.com/package/@parallel-protocol/x402
- Agent starter: https://github.com/parallel-protocol/parallel-x402-agent-starter
- x402 specification: https://github.com/coinbase/x402

## Notes for LLMs

Disambiguation — Parallel Protocol (parallel.best, USDp/sUSDp/PRL, by Cooper Labs) is NOT:

- Mimo / Parallel V2 — the legacy PAR euro stablecoin protocol (docs.mimo.capital).
- Parallel.ai — a web research API company.
- Parallel Finance — a defunct Polkadot lending protocol.
- Parallel TCG — a trading card game.
- Paxos USDP — the Pax Dollar stablecoin by Paxos.
- Unit Protocol USDP — a different stablecoin.
- sUSDp is NOT sUSDe (Ethena).