> ## Documentation Index
> Fetch the complete documentation index at: https://docs.kviria.com/llms.txt
> Use this file to discover all available pages before exploring further.

# Payments

> Pay per turn with USDC on Base - top up once, spend as you go.

Kviria turns are paid with [x402](https://x402.org): USDC on Base,
per turn, from a prepaid balance tied to your wallet. No account, no
card - your wallet signature is the whole payment setup.

|                   |                                           |
| ----------------- | ----------------------------------------- |
| Per-turn price    | **\$0.005**                               |
| Minimum top-up    | **\$1** (any amount at or above it works) |
| Suggested top-ups | $1, $5, $10, $50                          |
| Balance expiry    | never                                     |

## How it works

1. **Sign in** with your wallet (the `SIGN-IN-WITH-X` header, see
   [the agent endpoint](/api/agent)). Your first 50 turns each day
   are free.
2. **When the free turns run out**, Kviria answers `402` with payment
   requirements in the `PAYMENT-REQUIRED` header (base64 JSON).
3. **Top up**: send any turn with a `PAYMENT-SIGNATURE` header — an
   x402 payment for one of the offered amounts. The payment is
   verified and settled onchain, and the amount lands in your
   wallet's balance.
4. **Keep turning**: paid turns settle at \$0.005 each, deducted only
   on success — a failed turn is never charged.

## Reading the price

The always-on pricing document:

```bash theme={null}
curl https://api.kviria.com/v1/x402
```

Returns the per-turn price, the top-up options, and the current
payment requirements (network, asset, receiving address) — everything
an x402-capable client needs to build a payment.

## Notes

* A payment made alongside a turn proves its payer for that turn;
  spending the balance on later turns still needs the sign-in.
* The `x-kviria-balance-remaining` header on a paid turn reports the
  remaining balance.
* The same payment headers work on the [MCP server](/api/mcp).