# Monetize for the agentic internet

**Charge per API call in stablecoins using x402 — no subscriptions, no invoicing, no credit cards.** A caller pays for exactly what they consume, settled on Radius in ~500ms at ~0.00001 USD per transaction.

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## The problem with existing API monetization

Traditional API monetization requires accounts, credit cards, and subscription management. None of these work for AI agents. Agents operate autonomously. They don't manage subscriptions, don't have credit cards, and make purchasing decisions at volumes no human can authorize in real time.

Existing models break in two ways:

1. **Friction at onboarding** — agents can't sign up for a paid plan without human intervention
2. **Wrong pricing granularity** — subscriptions bundle access; agents need per-request pricing at fractions of a cent

x402 solves both. The HTTP request carries its own payment.

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## How x402 works

x402 embeds stablecoin payments directly into HTTP request-response flows using the existing `402 Payment Required` status code:

1. Agent sends a standard HTTP request to your endpoint
2. Your server returns `HTTP 402` with payment terms (price, accepted tokens, facilitator URL)
3. Agent signs a payment using its wallet and resubmits the request with payment proof in the header
4. x402 facilitator verifies payment and settles it on Radius (~500ms)
5. Your server delivers the resource

No checkout page. No account creation. No human in the loop. The agent discovers, pays, and receives — autonomously.

---

## Why Radius for settlement

x402 is settlement-layer agnostic. The Radius facilitator settles x402 payments on Radius Network.

At sub-cent price points, settlement cost determines whether the business model is viable:

| Settlement layer | Cost per transaction | Viable at 0.001 USD/call | Viable at 0.0001 USD/call |
|-----------------|---------------------|--------------------------|---------------------------|
| Stripe (card) | ~0.30 USD + 2.9% | No — fee exceeds revenue | No |
| Base | 0.001–0.01 USD | No — fee matches revenue | No |
| Solana | ~0.00025 USD | Yes | Marginal |
| **Radius** | **~0.00001 USD** | **Yes** | **Yes** |

Radius settlement cost is noise — 1% of a 0.001 USD call, 10% of a 0.0001 USD call. The economics work at any price point above 0.0001 USD per request.

---

## Integration

Add x402 middleware to any Node.js HTTP server. Your existing application logic does not change — the middleware handles payment verification before the request reaches your code.

```typescript
import { paymentMiddleware } from "@coinbase/x402-express";

app.use(paymentMiddleware({
  facilitatorUrl: "https://facilitator.testnet.radiustech.xyz",
  routes: {
    "/api/data": {
      price: "$0.001",
      network: "radius",
      description: "Data query",
    },
    "/api/inference": {
      price: "$0.0005",
      network: "radius",
      description: "Inference call",
    },
  },
}));
```

The Radius x402 facilitator is live on testnet. Mainnet access is available through the Radius team.

→ [x402 Integration Guide](https://docs.radiustech.xyz/llms/x402-integration-guide.md) — full implementation walkthrough

---

## Economics at scale

At 0.00001 USD settlement cost per transaction:

| Daily API calls | Settlement cost | Revenue at 0.001 USD/call | Net margin |
|----------------|----------------|--------------------------|------------|
| 100K | 1.00 USD | 100 USD | ~99% |
| 1M | 10.00 USD | 1,000 USD | ~99% |
| 10M | 100.00 USD | 10,000 USD | ~99% |
| 1B | 10,000 USD | 1,000,000 USD | ~99% |

Settlement cost scales linearly with volume and stays below 1% of revenue at any price above 0.001 USD per call.

---

## What you can monetize

Any HTTP endpoint that responds to a request can charge for that response:

- **Data APIs** — weather, market data, geocoding, search, financial data
- **AI inference** — LLM calls, image generation, classification, specialized models
- **Compute** — GPU time, CPU bursts, vector search, storage access
- **Content** — articles, datasets, research papers, media, paywalled documentation
- **Agent services** — agents selling capabilities to other agents (translation, summarization, routing, arbitration)
- **Pay-per-crawl** — content owners charging AI scrapers per page crawled

The pattern is identical across all use cases: HTTP request → 402 response → payment header → resource delivery.

---

## Agent discovery

For agents to find and pay for your API autonomously, expose payment terms through standard machine-readable channels:

- **`/.well-known/payment`** — x402 payment manifest
- **`/llms.txt`** — human and agent-readable description of your API and payment model
- **OpenAPI spec** — annotate endpoints with x402 payment extension fields

Agents using x402-aware clients (Coinbase AgentKit, Skyfire, and others) will discover payment requirements automatically and pay without human intervention.

---

## Further reading

- [x402 Integration Guide](https://docs.radiustech.xyz/llms/x402-integration-guide.md) — complete server and client implementation
- [Why Radius for Agent Payments](https://docs.radiustech.xyz/llms/why-radius.md) — settlement layer context
- [No Native Token](https://docs.radiustech.xyz/llms/no-native-token.md) — why stablecoin fees make micropayments viable
- [Real-time API Metering](https://docs.radiustech.xyz/use-cases/real-time-api-metering.md) — complete TypeScript implementation with viem