AI agent payments on the XRP Ledger

What is x402?

x402 is an open payment protocol built on the HTTP 402 Payment Required status code, a response that was reserved in the original web spec and left unused for decades. x402 puts it to work: a client requests a resource, the server replies 402 with machine-readable payment terms, and the client retries the same request carrying a signed payment. The server verifies it, settles on-chain, and returns the resource. No account, no API key, no checkout page. It is designed for software, and it is the emerging standard for how AI agents pay for what they consume.

How x402 works on the XRP Ledger

The XRP Ledger is a natural settlement layer for this: payments finalize in three to five seconds, fees are a fraction of a cent, and it has native stablecoins. In an XRPL x402 flow:

1. 1

   Agent requests a paid resource

   An AI agent calls an API. The server responds 402 with the price and the XRPL account to pay.

2. 2

   Agent presigns an XRPL Payment

   The agent signs a standard Payment transaction for the amount and attaches the signed blob to the retried request. It never shares a private key.

3. 3

   Facilitator verifies and settles

   A facilitator validates the presigned payment and submits it to the ledger. It never signs on the payer's behalf and never custodies funds.

4. 4

   Resource is returned

   Once the Payment validates on-ledger, the server returns the content along with the settlement reference.

Agents can pay in native XRP or in issued tokens including RLUSD and USDC. Stablecoin settlement is the part that makes this practical, because a per-request price should not swing with the market between one call and the next.

How big is it, really?

The facilitator operator has cited nearly one million XRPL agent transactions. We cannot audit their cumulative total, so we do not restate it as fact. What we can do is watch the ledger directly, and there the activity is real and continuous: scanning recent validated ledgers, XRPL x402 payments settle at a steady rate of hundreds per hour, each one identifiable by its facilitator fingerprint. The amounts are true micropayments (fractions of a cent), so the story is transaction count, not dollar volume. For context, most x402 volume to date has settled on other chains, primarily in USDC on Base and Solana. XRPL x402 is younger, and now measurable.

Frequently asked questions

What is x402?

x402 is an open payment protocol built on the HTTP 402 “Payment Required” status code. It lets a client, typically an AI agent, pay for an API call or digital service inline with a normal HTTP request, with no account and no API key. The server answers a request with a 402 and machine-readable payment terms, the client retries with a signed payment, and settlement happens on-chain.

How does x402 work on the XRP Ledger?

On XRPL, the payer signs a standard Payment transaction and hands the signed blob to the server in the x402 payload. A facilitator verifies the payment and submits it to the ledger. The facilitator never holds the payer's keys and never signs on their behalf. Settlement is a normal on-ledger Payment, so it clears in three to five seconds.

Which assets can AI agents pay with on XRPL?

Native XRP plus issued tokens (IOUs), including RLUSD, Ripple's dollar stablecoin, and USDC. Stablecoin settlement is what makes agent payments practical, because a per-request price stays stable in dollar terms.

How many x402 payments have settled on XRPL?

The facilitator operator has cited nearly one million XRPL agent transactions, a cumulative total we cannot independently audit. What we can confirm straight from the ledger is a steady, continuous stream: scanning recent validated ledgers, XRPL x402 payments settle at a rate of hundreds per hour. They are micropayments, so the meaningful metric is transaction count, not dollar volume. Most overall x402 activity still settles on Base and Solana in USDC.

Can you track x402 payments on-chain?

Yes, for the t54 facilitator, currently the primary x402 facilitator on XRPL. Its payments carry a deterministic fingerprint: SourceTag 804681468 (t54's default source tag), a memo tagged t54-xrpl-x402, and an InvoiceID set to the SHA-256 of the invoice. We scan validated ledgers for that fingerprint and count the matches, which anyone running a public XRPL node can reproduce. A different facilitator would use its own source tag, which we would add.