L402 Producer API: Agents That Earn

The Key Differentiator

Until now, AI agents could only spend money. With the L402 Producer API, your agents can earn money too. This is true agentic commerce — agents that both buy and sell services autonomously.

The L402 Producer API lets Agentic Commerce subscribers turn their AI agents into service providers. Instead of just consuming paid APIs, your agent can create L402 payment challenges and verify payments before granting access to its own capabilities.

The Two Sides of Agentic Commerce

Side	What It Does	Who Pays	MCP Tools
Consumer (existing)	Agent accesses paid APIs	Your agent pays	access_l402_resource, pay_l402_challenge
Producer (new)	Agent charges for its services	Other agents pay you	create_l402_challenge, verify_l402_payment

Both sides use the same L402 protocol. The difference is direction: consumers pay invoices, producers create them.

Prerequisites

• Agentic Commerce subscription — Individual ($99/mo) or Business ($299/mo)
• LIGHTNING_ENABLE_API_KEY environment variable set to your merchant API key
• A configured payment provider (Strike or OpenNode) on your Lightning Enable account

{
  "mcpServers": {
    "lightning-enable": {
      "command": "dotnet",
      "args": ["tool", "run", "lightning-enable-mcp"],
      "env": {
        "STRIKE_API_KEY": "your-strike-api-key",
        "LIGHTNING_ENABLE_API_KEY": "your-merchant-api-key"
      }
    }
  }
}

Consumer Tools Are Free

The consumer tools (access_l402_resource, pay_l402_challenge, pay_invoice, etc.) require no subscription — just a wallet. Only the producer tools (create_l402_challenge, verify_l402_payment) require an Agentic Commerce subscription.

How It Works

The full agent-to-agent commerce flow:

┌──────────────────┐                    ┌──────────────────┐
│  Requesting Agent │                    │  Producer Agent   │
│  (Consumer)       │                    │  (Your Agent)     │
└────────┬─────────┘                    └────────┬─────────┘
         │                                        │
         │  1. "I need weather data"              │
         │──────────────────────────────────────> │
         │                                        │
         │                                        │  2. create_l402_challenge(
         │                                        │       resource="/api/weather",
         │                                        │       priceSats=50,
         │                                        │       description="7-day forecast"
         │                                        │     )
         │                                        │
         │  3. HTTP 402 Payment Required          │
         │     + Lightning invoice + macaroon     │
         │ <──────────────────────────────────────│
         │                                        │
         │  4. pay_l402_challenge(invoice, mac)   │
         │  ─ ─ ─ ─ ─ ─ ─ (pays invoice) ─ ─ ─ >│
         │                                        │
         │  5. "Here's my L402 token:             │
         │      macaroon:preimage"                │
         │──────────────────────────────────────> │
         │                                        │
         │                                        │  6. verify_l402_payment(
         │                                        │       macaroon, preimage
         │                                        │     )
         │                                        │
         │  7. Access granted + response data     │
         │ <──────────────────────────────────────│

MCP Tools

create_l402_challenge

Create an L402 payment challenge to charge another agent or user for accessing a resource.

Parameters:

Parameter	Type	Required	Description
resource	string	Yes	Resource identifier — URL, service name, or description of what you're charging for
priceSats	long	Yes	Price in satoshis to charge
description	string	No	Description shown on the Lightning invoice

Example:

User: When another agent asks for weather data, charge them 50 sats.

Claude: [Uses create_l402_challenge with resource="/api/weather/forecast",
         priceSats=50, description="7-day weather forecast"]

L402 challenge created!
- Invoice: lnbc500n1p3xyza...
- Price: 50 sats
- Resource: /api/weather/forecast

Share the invoice and macaroon with the requesting agent.
After they pay, they'll send you an L402 token (macaroon:preimage).
Use verify_l402_payment to confirm payment before granting access.

Response:

{
  "success": true,
  "challenge": {
    "invoice": "lnbc500n1p3xyza...",
    "macaroon": "AgELbGlnaHRuaW5n...",
    "paymentHash": "abc123def456...",
    "expiresAt": "2026-03-13T14:30:00Z"
  },
  "resource": "/api/weather/forecast",
  "priceSats": 50,
  "instructions": {
    "forPayer": "Pay the Lightning invoice, then present the L402 token...",
    "tokenFormat": "L402 {macaroon}:{preimage}",
    "verifyWith": "After receiving the L402 token from the payer, use verify_l402_payment to confirm payment before granting access."
  },
  "message": "L402 challenge created for 50 sats. Share the invoice with the payer."
}

---

verify_l402_payment

Verify an L402 token (macaroon + preimage) to confirm payment was made. Use this after a payer presents an L402 token, before granting access to the resource.

Parameters:

Parameter	Type	Required	Description
macaroon	string	Yes	Base64-encoded macaroon from the L402 token
preimage	string	Yes	Hex-encoded preimage (proof of payment)

Example:

User: The requesting agent sent this L402 token. Verify it.

Claude: [Uses verify_l402_payment with macaroon="AgEL...", preimage="7f8a9b..."]

Payment verified! The agent has paid 50 sats for /api/weather/forecast.
Granting access now.

Response (valid):

{
  "success": true,
  "valid": true,
  "resource": "/api/weather/forecast",
  "message": "Payment verified. The payer has paid — you can now grant access to the resource."
}

Response (invalid):

{
  "success": true,
  "valid": false,
  "message": "Payment verification failed. The token is invalid or the invoice has not been paid. Do NOT grant access."
}

Challenge Idempotency

When the same resource and price are requested within 60 seconds from the same client, the API returns the same invoice and macaroon instead of creating a new one. This prevents duplicate invoices when agents retry requests or when network issues cause repeated calls.

Idempotency is determined by:

• Client identifier — the X-Idempotency-Key request header, or the client's IP address if no header is provided
• Resource — the resource identifier passed in the request
• Price — the satoshi amount

If you need a fresh challenge for the same resource, either wait 60 seconds or use a different X-Idempotency-Key.

REST API Endpoints

The MCP tools call these endpoints under the hood. You can also call them directly from your own code.

POST /api/l402/challenges

Create an L402 challenge.

Headers:

Header	Required	Description
X-API-Key	Yes	Your Lightning Enable merchant API key
X-Idempotency-Key	No	Idempotency key (max 256 chars). Same key within 60s returns same challenge.

Request:

curl -X POST https://api.lightningenable.com/api/l402/challenges \
  -H "X-API-Key: YOUR_MERCHANT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "resource": "/api/weather/forecast",
    "priceSats": 50,
    "description": "7-day weather forecast"
  }'

Response (200 OK):

{
  "invoice": "lnbc500n1p3xyza...",
  "macaroon": "AgELbGlnaHRuaW5n...",
  "paymentHash": "abc123def456...",
  "expiresAt": "2026-03-13T14:30:00Z",
  "resource": "/api/weather/forecast",
  "priceSats": 50
}

Error Responses:

Status	Reason
400	Invalid request (missing resource, invalid price)
401	Missing or invalid API key
403	L402 not enabled on your plan — upgrade to Agentic Commerce

---

POST /api/l402/challenges/verify

Verify an L402 token.

Headers:

Header	Required	Description
X-API-Key	Yes	Your Lightning Enable merchant API key

Request:

curl -X POST https://api.lightningenable.com/api/l402/challenges/verify \
  -H "X-API-Key: YOUR_MERCHANT_API_KEY" \
  -H "Content-Type: application/json" \
  -d '{
    "macaroon": "AgELbGlnaHRuaW5n...",
    "preimage": "7f8a9b2c3d4e5f6a7b8c9d0e1f2a3b4c5d6e7f8a9b0c1d2e3f4a5b6c7d8e9f0a"
  }'

Response (200 OK — valid token):

{
  "valid": true,
  "resource": "/api/weather/forecast",
  "merchantId": 42,
  "amountSats": 50,
  "paymentHash": "abc123def456..."
}

Response (200 OK — invalid token):

{
  "valid": false,
  "error": "Preimage does not match payment hash"
}

End-to-End Example: Weather Data Agent

Here is a complete example of a producer agent that charges for weather data.

Producer Agent Setup

{
  "mcpServers": {
    "lightning-enable": {
      "command": "dotnet",
      "args": ["tool", "run", "lightning-enable-mcp"],
      "env": {
        "STRIKE_API_KEY": "your-strike-key",
        "LIGHTNING_ENABLE_API_KEY": "your-merchant-api-key"
      }
    }
  }
}

Producer Agent Behavior

Requesting Agent: "I need the 7-day forecast for New York City."

Producer Agent (Claude):
1. [Uses create_l402_challenge(
     resource="/api/weather/forecast/nyc",
     priceSats=25,
     description="7-day NYC weather forecast"
   )]

2. Returns to requesting agent:
   "Access to this forecast costs 25 sats.
    Pay this invoice: lnbc250n1p3...
    Then send me: L402 AgEL...:your_preimage"

Requesting Agent:
3. [Uses pay_l402_challenge(invoice="lnbc250n1p3...", macaroon="AgEL...")]
4. "Here's my token: L402 AgEL...:7f8a9b2c..."

Producer Agent (Claude):
5. [Uses verify_l402_payment(macaroon="AgEL...", preimage="7f8a9b2c...")]
6. Payment verified! Now fetching the forecast...
7. "NYC 7-Day Forecast:
    Monday: Sunny, 72F
    Tuesday: Partly cloudy, 68F
    ..."

Consumer Agent Setup

The consumer agent only needs a wallet — no subscription required:

{
  "mcpServers": {
    "lightning-enable": {
      "command": "dotnet",
      "args": ["tool", "run", "lightning-enable-mcp"],
      "env": {
        "STRIKE_API_KEY": "consumer-strike-key"
      }
    }
  }
}

Use Cases

AI Research Agent

Charge other agents for access to your curated research database:

create_l402_challenge(
  resource="/research/market-analysis",
  priceSats=100,
  description="Q1 2026 market analysis report"
)

Code Review Agent

Offer automated code review as a paid service:

create_l402_challenge(
  resource="/services/code-review",
  priceSats=500,
  description="Automated code review with security analysis"
)

Data Aggregation Agent

Sell aggregated data from multiple sources:

create_l402_challenge(
  resource="/data/crypto-sentiment",
  priceSats=50,
  description="Real-time crypto sentiment score from 10 sources"
)

Translation Agent

Charge per translation request:

create_l402_challenge(
  resource="/translate/en-to-ja",
  priceSats=10,
  description="English to Japanese translation"
)

Security Considerations

Always Verify Before Granting Access

Never grant access based on a payer claiming they paid. Always call verify_l402_payment to cryptographically confirm:

• The preimage matches the payment hash (SHA256(preimage) == payment_hash)
• The macaroon signature is valid (not tampered with)
• The macaroon is bound to the correct resource and merchant

Token Binding

Each L402 token is bound to:

• The resource it was issued for
• The merchant who issued it
• The amount that was charged

A token purchased for one resource cannot be reused for another, even on the same merchant.

Idempotency Keys

Use the X-Idempotency-Key header to prevent duplicate invoices in retry scenarios. Without it, the client's IP address is used for idempotency, which works but is less precise.

Next Steps

• MCP Complete Guide — Full tool reference for all 17 MCP tools
• API Monetization — Monetize existing APIs with the L402 proxy (no code changes)
• AI Agent Integration — Consumer-side L402 tools and wallet setup
• L402 API Reference — Complete L402 protocol reference