Analysis | Documentation reviewed September 19, 2026.
An Arc application and an HTTP agent can now reach D20DAO through different payment paths. The contract route has a configurable service fee plus transaction gas. The agent API advertises a fixed 0.05 USDC call price through x402.
The SDK records a September 18 change to Arc Mainnet pricing: a 0.02 USDC minimum, multiplier of three and 300,000-gas fulfillment overhead. Testnet retains the older 0.08 minimum and multiplier of five. Mixing the two produces a misleading budget.
For a 100,000-gas callback, the mainnet formula at an assumed 20-gwei base fee is max(0.02, 3 × 20 × 10^-9 × 400,000), or 0.024 USDC. At an assumed 176 gwei it becomes 0.2112 USDC. These are calculations using documented parameters, not live quotes; transaction gas is additional and pricing can change.
The HTTP API price buys a different service boundary: the provider opens the underlying randomness request. At 0.05 USDC, 100 paid calls have a listed service cost of 5 USDC, before any caller-side Gateway or network costs. One call can return multiple values where the operation allows it, so a die roll and a call are not necessarily the same billing unit.
Applications should decide which outcomes can safely share a request before purchasing them. Onchain fees, API payments and application prizes have separate settlement and refund rules. Quote the intended route instead of assuming a fixed price applies to both.
Sources: SDK pricing reference, agent API guide, API refund policy.
Related reading: D20DAO reports 470 Arc testnet requests completed within its 60-second deadline; D20DAO adds x402 payments for verifiable randomness at 0.05 USDC per call.