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What is MPCP?

The Machine Payment Control Protocol (MPCP) is a cryptographically enforced pipeline that enables machines—autonomous vehicles, robots, IoT devices, and AI agents—to perform financial transactions while remaining tightly constrained by policy.

Core Idea

Machines need to spend within bounds, not ask for approval on every transaction. MPCP provides that control layer:

Policy → PolicyGrant → Budget (SBA) → Payment (SPA) → Settlement → Verification

Each step produces signed artifacts that constrain the next. The machine can execute payments autonomously—as long as it stays within the bounds established when the session and budget were granted.

Key Characteristics

  • Bounded authorization — Pre-authorized spending envelopes (budgets) instead of per-transaction approval
  • Deterministic verification — Every settlement can be verified against the authorization chain
  • Settlement-agnostic — Works with XRPL, EVM chains, Stripe, hosted providers, and other rails
  • Offline-capable — Payments can complete when the network is unavailable (e.g., underground garage)
  • Policy-first — All spending derives from explicit policy rules (rails, assets, destinations, caps)

Who Is It For?

  • Fleet operators — Pre-authorize vehicles for parking, charging, tolls
  • Parking and charging infrastructure — Verify payments locally without calling a central backend
  • Autonomous system builders — Give machines spending authority with cryptographic guardrails
  • Backend teams — Integrate via SDK, service API, or CLI

What MPCP Is Not

MPCP does not:

  • Replace the settlement rail (XRPL, EVM, etc.) — it sits in front of it
  • Define how money moves — it defines how authorization is granted and verified
  • Require a specific blockchain — it is rail-agnostic
  • Handle human-present card flows — it is designed for machine-initiated, bounded spending

Next Steps