Overview
Prepaid credit billing and automation for developers and machines.
Last updated: Sep 30, 2026FTSOBest calls this API “x402 v1”: x402Version: 1 and the proprietary scheme ftsobest-prepaid-router. It is not the x402 V2 exact protocol (Coinbase/x402.org). A standard x402 client cannot use its standard payment flow to pay here. Use the SIWE, Bearer-Token and prepaid topup flow described in this module.
An on-chain topup buys USD-anchored credits. Metered usage is booked off-chain against one wallet balance; there is no gas transaction per API call. Watchdog subscriptions buy slot capacity. Creating a watch inside available capacity does not incur another purchase.
The eight metered data routes currently run in observe by owner decision and charge nothing. Prices are advertised, not collected. Watchdog is the paid product. Core wallet features remain free. See data routes and headers and Credits.
The API origin comes from the same server configuration used for SIWE, OpenAPI and discovery. Production uses ftso.app; use the server-advertised origin instead of the SEO site origin.
API_BASE='https://ftso.app'
curl "$API_BASE/api/x402/pricing?locale=en"observe advertises pricing without charging. enforce applies the existing authentication, terms, free-tier and credit checks. A billing dependency failure may leave a data response available with X-Payment-Notice: billing_unavailable. Treat that notice separately from an authentication or permission error; management-route security does not fail open. Mode changes are operator decisions, not actions a client can request.
The former /x402/docs#watchdog link lands here. Continue to the Watchdog API. Human setup guidance remains in Watchdog documentation.