Fixer Protocol
The unified payment rail for AI agents. One API, any protocol, x402 or MPP, every transaction settled on Solana with full on-chain transparency.
What is Fixer Protocol?
AI agents are spending money at scale, renting compute, calling APIs, and paying each other for services, hundreds of millions of times per month, at fractions of a cent per transaction. The infrastructure to support this is fragmented, protocol-locked, and largely opaque.
Fixer Protocol is the unified payment layer for AI agents. It abstracts both the x402 (Coinbase) and MPP (Stripe/Tempo) protocols behind a single developer interface, settles every transaction on Solana, and makes every payment verifiable on-chain in real time.
- Agents get wallets. Each agent or agent team gets a Solana wallet, provisioned in one line via SDK.
- Developers get one SDK. Call
fixer.pay(): the gateway detects the protocol automatically. - Finance teams get a ledger. Every transaction is recorded on Solana with a public
txHash. - Privacy is first-class. Optional Groth16 ZK proofs hide amount, sender, and receiver on demand.
Architecture
The Fixer Protocol gateway sits between your agent and any payment-gated service. Your agent calls fixer.pay() once; the gateway handles protocol detection, policy enforcement, settlement, and on-chain recording.
┌──────────────────────────────────────────────────────────────┐
│ Your AI Agent │
│ │
│ const rail = new FixerProtocol({ agentId, apiKey }); │
│ await fixer.pay({ endpoint: "https://api.service.com/..." }) │
└───────────────────────────┬──────────────────────────────────┘
│
▼
┌──────────────────────────────────────────────────────────────┐
│ Fixer Protocol Gateway │
│ │
│ ┌────────────────────┐ ┌───────────────────────────────┐ │
│ │ Protocol Detector │ │ Spend Policy Engine │ │
│ │ x402 vs MPP │ │ Budgets · Allowlists · Limits│ │
│ └────────┬───────────┘ └───────────────────────────────┘ │
│ │ │
│ ▼ │
│ ┌────────────────────────────────────────────────────────┐ │
│ │ Payment Router │ │
│ │ x402 Handler MPP Handler │ │
│ │ ┌──────────────┐ ┌─────────────────┐ │ │
│ │ │ USDC · Solana│ │ Stablecoin/Card │ │ │
│ │ │ HTTP headers │ │ IETF sessions │ │ │
│ │ └──────┬───────┘ └───────┬──────────┘ │ │
│ │ └──────────┬─────────────┘ │ │
│ │ ▼ │ │
│ │ ┌─────────────────────────────────────┐ │ │
│ │ │ ZK Privacy Layer (optional) │ │ │
│ │ │ Groth16 proofs · ElGamal encryption │ │ │
│ │ └───────────────────┬─────────────────┘ │ │
│ │ ▼ │ │
│ │ Solana Settlement Bridge │ │
│ └────────────────────────────────────────────────────────┘ │
└───────────────────────────┬──────────────────────────────────┘
│
▼
┌──────────────────────────────────────────────────────────────┐
│ Solana Mainnet │
│ · Every payment recorded on-chain │
│ · <$0.001 per transaction · <1000ms finality │
│ · USDC settlement · fixerprotocol.sol on-chain program │
└──────────────────────────────────────────────────────────────┘
Key Features
fixer.pay() call handles x402 and MPP automatically. Protocol detection is transparent to the developer.txHash. Finance teams can audit directly, no third-party reporting layer.