x402 vs API Keys e faturamento tradicional

API keys identify clients

API keys are useful for authentication, quota management, analytics, and account-level permissions. They are not a payment proof by themselves.

If you only use API keys for billing, you usually need invoices, prepaid balances, or a separate checkout flow.

x402 verifies payment at request time

x402 attaches the payment requirement to the resource and lets the client pay before access is granted. This is helpful when the buyer may be an agent, script, or external service.

The payment payload can be checked against amount, resource, method, expiry, and nonce so the server knows what was paid for.

When to use each model

Use API keys when you need long-lived accounts, dashboards, quotas, or access management. Use x402 when a single request should be independently payable.

For production systems, the strongest setup is often both: API keys for merchant/server identity and x402 for paid resource access.

• Subscriptions: best for bundled monthly access
• Prepaid credits: best for predictable platform accounts
• x402: best for per-request agent and API payments
• Traditional checkout: best for human purchase flows