Skip to main content
On EVM, a sponsored send lets the user pay the fee in an ERC-20 token instead of native gas. You bring your own bundler and paymaster. For the model, see Sponsorship.

​
Configure the infrastructure

Set both bundlerUrl and paymasterUrl on the client config. They are required together. With only one, the chain falls back to self-pay.
Many providers (Pimlico, Alchemy) serve both from one endpoint; pass the same URL twice. requireSponsorship: true makes a fee-token send throw SponsorshipUnavailableError (before anything is signed) if the sponsored rail is not reachable, naming which side is missing. Leave it false (the default) to let such a send degrade silently to self-pay.

​
Send with a fee token

Trigger the send through the provider with an EIP-5792 wallet_sendCalls request. The per-send fee token rides in the paymasterService capability’s context:
A single-token paymaster (for example, Circle USDC) can omit context.token; the provider then falls back to the chain’s default registry fee token. If you use wagmi, its useSendCalls produces the same request.

​
Confirm which rail ran

The returned id is the intent id. Check the rail rather than assuming your configuration took effect: use wallet_getCallsStatus, or on the core send path inspect receipt.rail. A sponsored EVM receipt has rail: "sponsored", an id that is a userOpHash, and status: "pending" until the bundler reports a receipt. See Receipts.