Skip to main content

​
Overview

Meridian extends x402 with a proxy facilitator architecture. Standard x402 transfers funds directly from payer to recipient; Meridian routes settlement through a facilitator contract instead:
This one change is what enables fee handling, batch settlement, cross-chain routing, cashback, and organization-scoped payment management on top of the plain x402 flow. On chains with native EIP-3009 support, Meridian settles standard x402 exact payloads through the facilitator; on chains without an EIP-3009-compatible token (MegaETH, BSC, BOT chain), Meridian settles via Permit2 through x402ExactPermit2Proxy. The upto scheme (usage-based pricing) settles via Permit2 through x402UptoPermit2Proxy on every supported chain. See Payment Types for how the facilitator routes each payload type.

​
X402ProxyFacilitator.sol (V6)

The facilitator is a UUPS-upgradeable contract, currently at version 6.
  • Payment Methods: EIP-3009 transferWithAuthorization (USDC), ERC-2612 transferWithPermit, and Permit2 transferWithPermit2 / transferWithPermit2Upto
  • Instant Settlement: Same-chain payments are settled to the recipient during payment execution
  • Batch Settlement: One signed authorization can settle multiple payments in a single transaction (batchTransferWithAuthorization / batchTransferWithPermit2), each item with its own recipient, platform, and fee
  • Fee Handling: Platform and treasury fees accrue inside the facilitator and are withdrawn via withdrawPlatformFees / withdrawTreasuryFees
  • MRDN Cashback: On Base, USDC payments earn MRDN cashback priced via Aerodrome TWAP — the rate starts at 2% and decays as total cashback is distributed, capped at $5 per transaction
  • Cross-Chain Support: The same entrypoint initiates cross-chain settlement through Across on supported networks, authenticated by a backend-signed EIP-712 message

​
x402ExactPermit2Proxy.sol (Non-EIP-3009 Chains)

Integrations on chains without EIP-3009-compatible tokens (MegaETH, BSC, BOT chain) use Permit2 settlement through the Meridian facilitator:
  • Flow: Users approve Permit2 once, then sign a Permit2 witness authorization off-chain for each payment
  • Token model: paymentRequirements.asset is the ERC-20 token address being paid
  • Facilitator binding: payTo and witness.to stay bound to the Meridian facilitator
  • Settlement: Meridian settles through transferWithPermit2, not through the buyer submitting a transaction

​
x402UptoPermit2Proxy (upto scheme)

The upto scheme uses the same Permit2 flow with x402UptoPermit2Proxy as the signed spender (same address on every chain). The buyer authorizes a maximum amount; Meridian settles the actual usage amount through transferWithPermit2Upto. Differences from the exact proxy:
  • Witness shape: { to, facilitator, validAfter } — the extra facilitator field binds which contract may choose the settled amount; both to and facilitator stay bound to the Meridian facilitator
  • Settled amount: 0 < settleAmount ≤ permit.permitted.amount, passed by the seller at settle time (paymentRequirements.extra.settleAmount); fees and cashback apply to the settled amount only

​
MRDN Token

MRDN (Meridian, 18 decimals) has a fixed canonical supply of 1 billion tokens on Base and uses LayerZero’s Omnichain Fungible Token (OFT) standard to move between Base and Robinhood Chain. The Base adapter locks canonical MRDN when bridging out; the Robinhood OFT mints the corresponding representation and burns it when MRDN returns to Base.

​
Deployed contracts

​
LayerZero route

The route uses six shared decimals and is open in both directions. OFT send messages use msgType 1 with an enforced destination receive-gas limit of 100,000. LayerZero Labs and Nethermind are the two required DVNs on each direction. Ownership and LayerZero Endpoint delegation are held by the Meridian Safe at 0x37E9CA7154F539113626903edf1f5a14714A0faa.

​
Solana (SVM)

On Solana, Meridian settles through the meridian_x402 program instead of a Solidity facilitator. Solana needs no EIP-3009: a transaction can carry multiple signers, so the payer signs the settlement transaction as their USDC token authority and the facilitator co-signs as fee payer and submits it. Settlement is atomic — the program splits fees and the recipient’s net directly from the payer’s token account in one transaction, with no escrow hop. The program is live on both solana (mainnet) and solana-devnet. See Solana Program for the architecture, accounts, and fee math, and Solana payments for an end-to-end integration guide.

​
How a Payment Flows

  1. Authorization Signing: Payer signs a payment authorization with amount, recipient context, and network details.
  2. Verification: Server verifies signature and authorization parameters.
  3. Transfer Execution: Meridian executes settlement through the facilitator — transferWithAuthorization for native EIP-3009 tokens, transferWithPermit2 via the proxy elsewhere.
  4. Fee Application: Recipient and fee amounts are handled during settlement processing.
Payments are linked to your organization: API keys authenticate verification and settlement, the recipient wallet is configured in organization settings, and every payment lands in your organization’s transaction history in Command Centre.