How does Hilt use x402?

Hilt uses x402 as the HTTP 402 Payment Required protocol for protected resources. The response gives agents a machine-readable payment requirement; Hilt verifies the resulting Solana USDC settlement and turns it into receipt, entitlement, webhook, support, and audit state.

What does Hilt add to x402?

Hilt adds the operating layer around the payment: payment session, proof handling, Solana USDC settlement verification, receipt, entitlement, webhook, support context, analytics, and audit history.

Can x402 be used for AI agents and APIs?

Yes. A protected endpoint can return HTTP 402 when payment is needed, settle the buyer's PAYMENT-SIGNATURE through Hilt, then check durable access or atomically consume metered usage before serving the resource.

How does Hilt prevent the same metered unit being used twice?

The protected-resource server calls Hilt's atomic entitlement-consumption route with a stable idempotency key before serving each billable operation. Concurrent requests cannot consume the same final unit twice.

x402 and Hilt Pay API

HTTP 402 payments that turn into real access.

x402 gives agents and APIs a standard way to say payment is required. Hilt Pay API turns that requirement into the full operating record: payment session, proof, Solana USDC settlement, receipt, entitlement, webhook, support context, and audit trail.

In agentic payments language, x402 is the protocol layer. Hilt is the payment-to-access operating layer that makes the payment useful to the product after it settles.

Open the implementation guide View API pricing

Protocol flow

x402 gives agents the payment requirement.

x402 V2: PAYMENT-REQUIRED, PAYMENT-SIGNATURE, PAYMENT-RESPONSE

Launch settlement path: Solana USDC

Hilt: exact verification, receipt, entitlement, webhook, audit

Metered work: atomic consume before serving

Protected-resource loop

The API says payment required. Hilt makes the result operational.

Agent requests work

The protected server tries to consume one usage unit before running a billable operation.

Server returns HTTP 402

If usage is missing or exhausted, the server returns Hilt's x402 V2 PAYMENT-REQUIRED header.

Buyer signs and retries

The buyer signs the advertised Solana USDC transaction and retries with PAYMENT-SIGNATURE.

Hilt settles and records

POST /v1/access/x402/settle verifies the exact terms, settles, issues the receipt, and activates usage.

One unit is consumed

The server atomically consumes usage, serves the result, and keeps webhook and audit context.

x402 is the payment-required protocol

It gives agents a machine-readable way to understand what must be paid before an API, dataset, bot, or private tool responds.

Settlement is still a rail decision

For Hilt Pay API, the current public live settlement rail is Solana USDC. When a Hilt fee applies, hilt-exact binds both direct USDC transfers into one buyer-signed transaction.

Hilt is the operating layer

The valuable part is not only the payment requirement. It is the receipt, entitlement, webhook, support trail, analytics, and audit record after payment.

Copyable shape

A clean 402 response for agents.

Relay Hilt's encoded requirement exactly. The buyer returns PAYMENT-SIGNATURE; the server returns PAYMENT-RESPONSE after verified settlement.

HTTP/1.1 402 Payment Required
PAYMENT-REQUIRED: eyJ4NDAyVmVyc2lvbiI6Miwi...
Content-Type: application/json

{
  "error": "payment_required",
  "external_product_id": "research-calls"
}