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MPP (Machine Payment Protocol) is a payment protocol designed for AI agents and automated systems. It is the superset of x402, supporting both Tempo stablecoin payments and Stripe card payments in a single unified flow.
Unlike x402 which only supports on-chain USDC, MPP adds Tempo network stablecoins and traditional card payments as additional options.

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How It Works

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Detailed Flow

  1. Agent calls GET /mpp/purchase?plan=<plan> without payment credentials
  2. MPP service returns 402 with a WWW-Authenticate: Payment challenge containing amount, currency, and recipient
  3. Agent signs the payment using Tempo Wallet or Stripe
  4. Agent retries the purchase request with Authorization: Payment credential
  5. MPP service verifies payment, creates a subscription, and returns an API Key

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Supported Payment Methods

MethodNetworkCurrencyGas FeeBest For
TempoTempo (chain ID 4217)USDC.e (ERC-20)Free (gas in stablecoin)AI agents, no ETH needed
StripeTraditionalUSD (card)N/AAgents with card access, no crypto needed
Tempo payments do not require native gas tokens — gas is paid in the stablecoin directly. This makes it ideal for AI agents that only hold stablecoins.

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API Endpoints

EndpointMethodDescription
/mpp/purchase?plan=<plan>GET / POSTPurchase a subscription via MPP
/mpp/pricingGETList available plans and payment methods
/mpp/healthGETHealth check

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Pricing Response

curl https://api.chainstream.io/mpp/pricing

{
  "plans": [
    { "name": "nano", "priceUsd": 5, "quotaTotal": 500000, "durationDays": 30 },
    { "name": "starter", "priceUsd": 199, "quotaTotal": 10000000, "durationDays": 30 }
  ],
  "currency": "USD",
  "paymentMethods": ["tempo", "stripe"],
  "note": "Prices in USD. Pay via MPP (Tempo stablecoin or Stripe card)."
}

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Purchase Response (Success)

{
  "status": "ok",
  "plan": "nano",
  "expiresAt": "2026-04-25T12:00:00.000Z",
  "apiKey": "cs_live_..."
}

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CLI Usage

The ChainStream CLI supports MPP as a payment option during the auto-purchase flow: 
chainstream token info --chain sol --address So11111111111111111111111111111111111111112
# → 402 → plan selection → choose "MPP Tempo" → payment → API Key saved
For agents without a ChainStream wallet, the CLI prints the Tempo command: 
tempo request "https://api.chainstream.io/mpp/purchase?plan=nano"

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Manual Integration (Tempo Wallet)

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Setup

Install the Tempo Wallet CLI and log in (one-time passkey authentication via browser): 
curl -fsSL https://tempo.xyz/install | bash
tempo wallet login
Tempo Wallet uses passkey (WebAuthn) authentication. The first setup requires a browser interaction. After that, the session persists and agent operations work without further browser interaction.

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Purchase

# Check your balance
tempo wallet balance

# Purchase a plan (auto-handles 402 → sign → retry)
tempo request "https://api.chainstream.io/mpp/purchase?plan=nano"
The Tempo CLI handles the WWW-Authenticate: Payment challenge automatically, signs the transaction, and returns the API Key on success.

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Compatible Wallets

Tempo is EVM-compatible (chain ID 4217). Any wallet holding USDC.e on Tempo works:
  • Tempo Wallet CLI (tempo request) — recommended, passkey auth, built-in MPP support
  • Any EVM wallet (MetaMask, Coinbase CDP, Privy) — add Tempo as custom network

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MPP vs x402

MPPx402
Payment methodsTempo stablecoin + Stripe cardOn-chain USDC only
NetworksTempo (chain ID 4217) + StripeBase (EVM) + Solana
Gas feeFree (Tempo) / N/A (Stripe)Free (facilitator)
Requires crypto walletNo (Stripe option available)Yes
Purchase endpoint/mpp/purchase/x402/purchase
ProtocolMPP (HTTP 402)x402 protocol
Best forAgents without crypto walletsAgents with USDC on Base/Solana

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Next Steps

x402 Payment Protocol

On-chain USDC payments via the x402 protocol

Billing & Units

Understand CU consumption and plan details