P402

P402 Protocol

AI payment router. Route across 300+ models, settle per request in USDC on Base or USDC.e on Tempo.

P402 sits between your AI application and every LLM provider. It handles intelligent multi-provider routing (cost / quality / speed / balanced), on-chain micropayment settlement via the x402 protocol and mppx on Base and Tempo, and spending guardrails for autonomous agents.

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Why P402

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Quick Start (VS Code / Cursor / Windsurf)

Install the extension — the MCP server is embedded, tools appear in Copilot agent mode immediately, no config files required:

ext install p402-protocol.p402

Then run P402: Configure API Key from the command palette.

→ VS Code Marketplace · Open VSX

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Quick Start (Claude Desktop / any MCP client)

{

"mcpServers": { "p402": { "command": "npx", "args": ["-y", "@p402/mcp-server"], "env": { "P402_API_KEY": "p402_live_..." } } } }

→ MCP docs · MCP Registry

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Quick Start (SDK)

npm install @p402/sdk

import P402Client from '@p402/sdk';

const p402 = new P402Client({ apiKey: process.env.P402_API_KEY });

// Drop-in OpenAI replacement — P402 picks the best provider const response = await p402.chat({ messages: [{ role: 'user', content: 'Explain x402 payments in one sentence.' }], p402: { mode: 'cost' } // cost | quality | speed | balanced });

console.log(response.choices[0].message.content); // p402_metadata: { provider: 'deepseek', cost_usd: 0.00031, latency_ms: 412 }

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Quick Start (CLI)

# Authenticate once

npx p402 login

Chat using the cheapest provider

npx p402 chat "What is x402?" --mode cost

Check facilitator health

npx p402 health

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Routing Modes

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Session Budgets

Enforce hard spending caps for autonomous agents:

// Create a $10 session — agent cannot spend a cent more

const session = await p402.createSession({ budget_usd: 10 });

// All chat requests are deducted from the session const response = await p402.chat({ messages, p402: { session_id: session.id, mode: 'cost' } });

// Check remaining budget const { budget } = await p402.getSession(session.id); console.log($${budget.remaining_usd} remaining);

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x402 Payments

x402 is a machine-native payment protocol using HTTP 402. AI agents pay for resources using gasless EIP-3009 USDC transfers on Base L2.

Client → signs EIP-3009 authorization

→ POST /api/v1/facilitator/verify → POST /api/v1/facilitator/settle Facilitator → executes transferWithAuthorization → pays gas (user pays zero gas) → returns { success, txHash, receipt }

Network: Base Mainnet (Chain ID: 8453) · Asset: USDC 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913

→ x402 payments guide

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A2A Protocol

P402 implements the Google A2A spec over JSON-RPC 2.0. Agents communicate through structured tasks, discover capabilities via /.well-known/agent.json, and settle payments via the x402 extension.

// Discover P402's capabilities

GET https://p402.io/.well-known/agent.json

// Submit a task POST https://p402.io/api/a2a { "jsonrpc": "2.0", "method": "tasks/send", "params": { ... } }

→ A2A protocol guide

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Packages

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Examples

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Docs

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Community

• Dashboard: p402.io/dashboard
• Docs: p402.io/docs
• Issues: GitHub Issues
• Security: See SECURITY.md for responsible disclosure
• Contributing: See CONTRIBUTING.md

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License

MIT © P402 Protocol