Choose between x402 and MPP

Both protocols achieve the same result: an agent pays for API access, the server verifies, work is done, results are stored. The choice of protocol depends on the agent’s wallet type, the chain it uses, and whether session payments are needed.

Decision table

If you need…	x402	MPP	Recommendation
Base chain (USDC)	✓	—	x402
Tempo chain (USDC.e)	—	✓	MPP
Off-chain signing (no gas for agent)	✓	—	x402
On-chain settlement first	—	✓	MPP
Session payments	—	✓	MPP
Maximum agent compatibility	✓	✓	Dual-protocol
Simple one-off request	✓	✓	Either
Coinbase AgentKit	✓	—	x402
Tempo-native agent	—	✓	MPP

Protocol comparison

	x402	MPP
Chain	Base	Tempo
Token	USDC	USDC.e
Agent signs	Off-chain ERC-3009 (no gas)	On-chain transaction (gas cost)
Settlement timing	Async (server submits after response)	Sync (agent submits before request)
Challenge header	`PAYMENT-REQUIRED`	`WWW-Authenticate`
Credential header	`PAYMENT-SIGNATURE`	`Authorization: Payment`
Session payments	No	Yes
Standard	x402 Foundation	IETF Internet Draft

For developers: use dual-protocol

As a developer building an API, use dual-protocol (the default). You don’t need to pick — your endpoint accepts both. The agent picks the protocol that matches its wallet.

// This is all you need — works with x402 and MPP agents
app.post('/analyse',
  payMiddleware({ price: '0.01', description: 'Analysis' }),
  vaultMiddleware(),
  handler
);

The only case where you’d want to restrict to one protocol is if your organisation only has a wallet on one chain. If your wallet is on Base, only x402 payments can settle there. If your wallet is on Tempo, only MPP payments can settle there. With dual-protocol configured and a wallet on each chain, you accept both.

For agents: picking the right protocol

An agent picks a protocol based on which challenge headers it can process and which wallet it has:

const hasX402Challenge = response.headers.has('payment-required');
const hasMPPChallenge  = response.headers.has('www-authenticate');
const agentHasBaseWallet  = true; // agent's capability
const agentHasTempoWallet = false;

if (hasX402Challenge && agentHasBaseWallet) {
  // Use x402 — sign ERC-3009 and submit PAYMENT-SIGNATURE
} else if (hasMPPChallenge && agentHasTempoWallet) {
  // Use MPP — send Tempo transaction and submit Authorization: Payment
} else {
  throw new Error('Agent cannot pay — no compatible wallet for available protocols');
}

Why Prudra defaults to dual-protocol

The agent payment ecosystem is young and fragmented. Some agents support x402, some MPP, some both. A server that only supports one protocol excludes agents that can only use the other. Dual-protocol eliminates this fragmentation problem for the developer. The challenge generation overhead is negligible — both challenges are built in one atomic call. The benefit (full agent compatibility) far outweighs the cost (a second header in the 402 response).

Dual-protocol overview — how both challenges fit in one response
How challenges are built — atomic challenge generation
x402 overview — x402 in depth
MPP overview — MPP in depth

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Choose between x402 and MPP