Comparison: x402 vs MPP vs AMP
An honest comparison of the three machine payment protocols.
Protocol overview
x402 (Coinbase) — HTTP 402 with per-request payments on Base (EVM). Simple, stateless, one on-chain transaction per call.
MPP (Tempo/Stripe) — extensible HTTP 402 framework with multiple payment methods (Tempo, Stripe, cards, Lightning, Solana). Supports sessions with off-chain vouchers. IETF specification.
AMP (Valeo) — Solana-native persistent channels. Off-chain metering, on-chain net settlement. Supports delegation, chaining, and multiple transports.
Feature matrix
| Feature | x402 | MPP | AMP |
|---|---|---|---|
| Payment model | Per-request | Per-request + sessions | Persistent channels |
| Runtime latency | Per-call | Per-call / near-zero (session) | Zero after open |
| Transport | HTTP only | HTTP + MCP | HTTP + MCP + WS + gRPC |
| Chain | Base (EVM) | Tempo, Solana, Lightning, cards | Solana native |
| On-chain txns / 1K calls | 1,000 | 2 (session) | ~3 |
| Streaming | No | SSE with vouchers | Native (any transport) |
| Delegation | No | No | Native |
| Credit support | No | No | Native (ACE-ready) |
| On-chain composability | Limited (EVM) | Varies | Full Solana DeFi |
| IETF standardization | No | Yes | No (open spec) |
| Fiat support | No | Yes (Stripe, cards) | No (crypto-native) |
| Service discovery | No | No | On-chain registry |
| Multi-channel netting | No | No | Stratum |
| Reputation | No | No | On-chain scoring |
Cost analysis (1,000 calls at $0.001/call)
| Protocol | On-chain txns | Gas cost |
|---|---|---|
| x402 (Base) | 1,000 | ~$1.00 |
| MPP session (Tempo) | 2 | ~2x Tempo tx cost |
| AMP (Solana) | ~3 | ~$0.00075 |
When to use what
x402 wins when:
- You want the simplest possible integration
- You're already on Base/EVM
- You only need one-off per-request payments
MPP wins when:
- You need multi-method support (crypto + cards + fiat)
- You want IETF-grade standardization
- You need Python or Rust SDKs today
AMP wins when:
- You're building on Solana and want native composability
- You need high-volume usage with minimal on-chain cost
- You need delegation (agent-to-agent budget forwarding)
- You need transport bindings beyond HTTP (MCP, gRPC, WebSocket)
- You want on-chain channel state that other programs can read and compose with
The real differentiator
MPP is a payment framework — flexible, multi-method, payment-rail agnostic. AMP is a financial state protocol — Solana-native, composable, persistent. They serve different architectural needs.