NexFlow Smart Meta-Facilitator (SMF)

The x402-native metered billing and routing brain for AI agents and SaaS APIs on Base.

NexFlow SMF routes, verifies, and settles x402 micropayments on Base. It acts as an intelligent intermediary between payers and facilitators, selecting the optimal route based on cost, latency, and reliability. This repository contains the on-chain settlement contracts, TypeScript SDK, agent manifest specification, and integration examples.

# 🎴 Browse AgentCard Catalog →

Discover AI agent services with x402 payment routing through NexFlow SMF. Submit your service to the catalog.

# 🧩 Skills (Cursor & AI agents)

Canonical list of NexFlow SMF skills. Each skill has a SKILL.md (for Cursor/agents) and lives in nexflow-smf-skills/. Machine-readable manifest: skills-manifest.json · API: GET https://api.nexflowapp.app/.well-known/skills (redirects to manifest).

| Skill | Description |
|- -- -- --|- -- -- -- -- -- -- -|
| List Facilitators | Discover active x402 facilitators by network/asset before quoting or paying. |
| Route Matrix | Compare priced routes (fees, latency) across facilitators for USDC on Base. |
| Route Quote | Get a single priced quote for a chosen facilitator before committing. |
| Settlement Receipt | Fetch a settlement receipt for a completed x402 payment for logs or audits. |
| Healthcheck | Ping NexFlow SMF for status and latency before routing payments. |
| Simulate Charge | See x402 pricing headers without performing a real payment. |
| Budget Plan | Turn a USDC budget into an approximate number of SMF API calls. |

# 🎴 Browse AgentCard Catalog

Discover NexFlow services as AgentCards, ready for AI agents and x402-aware clients:

https://nexflow-agentcards.pages.dev/

# Choose Your Path

# # Monetize an existing API at the edge (recommended)

Drop a Lambda@Edge function in front of CloudFront. Every request to a protected path must include a valid x402-payment header — otherwise the client gets a 402 Payment Required with payment instructions. No backend changes needed.

How it works:

1. viewer-request — Lambda calls /x402/verify with the payment proof (not billed). If valid, attaches a settlementIntentId and forwards to origin. If invalid, returns 402.
2. origin-response — Lambda reads the settlementIntentId. If origin status < 400, calls /x402/settle to confirm delivery (this is the billable event). Returns the response unchanged.

Get started in 15 minutes:

AWS CloudFront + Lambda@Edge Quickstart →

# # Use the NexFlow SMF SDK directly

For server-side integrations where you control the request lifecycle — route payments, verify intents, and trigger batch settlement from your own code.

npm install @nexflow-smf/smf

import { NexFlowSMFClient } from '@nexflow-smf/smf';

const smf = new NexFlowSMFClient({
  baseUrl: 'https://api.nexflowapp.app',
  apiKey: process.env.NEXFLOW_API_KEY!,
});

// Route a payment
const route = await smf.route({
  amount_wei: '1000000',
  token_address: '0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913',
  chain_id: 'eip155:8453',
  payment_id: 'order-123',
});

// Verify a payment intent
const result = await smf.verify({
  payment_intent: 'x402:1:base:0xabc...',
  recipient_address: '0xYourAddress...',
});

Full SDK documentation →

# What's in This Repo

| Path | Description |
|- -- -- -|- -- -- -- -- -- --|
| examples/aws-cloudfront-lambdaedge/ | 15-minute AWS quickstart — Lambda@Edge x402 pay-per-request gating |
| examples/basic-settlement.ts | End-to-end SDK example: route, verify, settle |
| sdk/ | Zero-dependency TypeScript SDK (@nexflow-smf/smf) |
| contracts/ | Solidity contracts for atomic batch settlement with Merkle proofs |
| docs/ | API reference, facilitator contract, production checklist |
| AGENT_MANIFEST_V1.md | Agent Manifest spec for machine-to-machine discovery |
| nexflow-smf-skills/ | Cursor-style agent skills (route-matrix, quote, receipt, facilitators, health, simulate, budget) |
| PRICING.md | Pricing model with example scenarios |

# Services Overview

| Service | Description | Status |
|- -- -- -- --|- -- -- -- -- -- --|- -- -- -- -|
| Smart Meta-Facilitator | Intelligent payment routing, verification, and batch settlement | Live |
| CloudFront Edge Gating | Lambda@Edge adapter for pay-per-request access via CloudFront | Live |
| Agent Manifest & Discovery | Machine-readable capability manifest for AI agent integration | Live |
| Pulse Scheduler | Metered job scheduling with x402 billing (cron, webhooks, tasks) | Live |
| Action Catalog | Pre-built metered actions (Shopify, Salesforce, data enrichment) | Live |

# Base Mainnet Contracts

| Contract | Address | Explorer |
|- -- -- -- -- -|- -- -- -- --|- -- -- -- -- -|
| AtomicBatchSettlement | 0x43A04228152115fDd5663B2Aa559Ebd84D17A49D | BaseScan |
| USDC | 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 | BaseScan |

# Environment Variables

| Variable | Required | Description |
|- -- -- -- -- -|- -- -- -- -- -|- -- -- -- -- -- --|
| NEXFLOW_API_KEY | Yes | Your NexFlow API key (nf_live_xxx or nf_test_xxx) |
| NEXFLOW_BASE_URL | No | Override API URL (default: https://api.nexflowapp.app) |

Sign up or log in at nexflowapp.app, go to Developers → API Keys, and click Create API key. Use that key with the examples in this repo.

Never commit API keys or secrets. Use environment variables or a secrets manager.

# Supported Networks & Tokens

| Network | Chain ID | Status |
|- -- -- -- --|- -- -- -- -- -|- -- -- -- -|
| Base mainnet | eip155:8453 | Primary |

| Token | Address | Decimals |
|- -- -- --|- -- -- -- --|- -- -- -- -- -|
| USDC | 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913 | 6 |

# Documentation

| Doc | What's inside |
|- -- --|- -- -- -- -- -- -- --|
| Facilitator API | /verify and /settle contracts, settlementIntentId lifecycle, error handling, retry guidance |
| API Reference | All endpoints (SMF core, x402 routing, agent discovery), SDK reference, contract ABI |
| Production Checklist | Idempotency, latency, CloudWatch logging, failure modes, key rotation |
| Pricing | Pulse metering, facilitator settle-only pricing, example scenarios |
| Agent Manifest | Machine-to-machine capability discovery spec |
| SDK README | Full SDK docs: installation, methods, error handling, utilities |

# Development

# # Building the SDK

cd sdk
npm install
npm run build       #  Build for production (CJS + ESM + types)
npm run dev         #  Watch mode
npm run typecheck   #  Type checking

# # Running Examples

#  SDK example
cd sdk && npm install
npx tsx ../examples/basic-settlement.ts

#  Lambda@Edge example
cd examples/aws-cloudfront-lambdaedge
npm install
npm run build   #  requires NEXFLOW_FACILITATOR_URL and NEXFLOW_API_KEY

# Contributing

We welcome contributions! See CONTRIBUTING.md for guidelines.

# Security

For security concerns, see SECURITY.md.

# License

MIT License — see LICENSE for details.

# Links

• Website: nexflowapp.app
• API: api.nexflowapp.app
• Skills manifest (machine-readable): skills-manifest.json · api.nexflowapp.app/.well-known/skills
• Agent Manifest: api.nexflowapp.app/.well-known/agent-manifest
• SDK on npm: @nexflow-smf/smf
• Settlement Contract: BaseScan
• Issues: GitHub Issues
• Optimism RetroPGF: Project

Built for the x402 ecosystem on Base