# Payments

> x402 setup for paid discovery workflows. You do not need payment setup for the free tier, `GET /health`, descriptors, docs, or `GET /verify`.

## Pricing

- 50 discovery workflows per day per IP are free.
- After the free tier, discovery workflows cost $0.002 USDC on Base.
- A workflow is one `/discover` call plus up to 5 free `/inspect` calls using the returned `query_id`.
- `/verify` is free and never returns a payment challenge.

## Auto-pay

```bash
export SIGILDEX_WALLET_KEY=<your-evm-private-key>
npx @sigildex/cli search "browser automation" --json
```

The CLI uses x402 to sign and retry paid requests when a wallet key is configured. For application integrations, fetch `/.well-known/x402.json` and handle the payment challenge returned by paid endpoints.

## Headers

Paid requests use `payment-signature`. Responses include `X-Sigildex-Version` and `X-Request-Id`; discovery responses also include rate-limit headers.

## Errors

`PAYMENT_REQUIRED` means the free discovery tier is exhausted and a valid payment is needed. `PAYMENT_FAILED` means payment verification failed. `PAYMENT_UNAVAILABLE` means the payment system is temporarily unavailable. No settlement occurs for failed application responses.