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·Transfa Team

What Is Fee Sponsorship on Tempo?

Fee sponsorship lets a third party pay Tempo transaction fees using domain-separated co-signatures. No Paymaster contracts or bundler infrastructure needed.

tempofee-sponsorshipgaslesstransactions

Fee sponsorship on Tempo lets a third party pay transaction fees on behalf of a user. The sender signs the transaction, a fee payer co-signs it, and the protocol charges the fee payer's stablecoin balance instead of the sender's. It works at the protocol level, without Paymaster contracts, bundlers, or smart contract wallets.

How it works

A sponsored transaction carries two signatures with domain separation:

  1. Sender signs with domain prefix 0x76, omitting the fee_token from their signing hash (delegating token choice to the fee payer)
  2. Fee payer signs with domain prefix 0x78, committing to the sender's address, fee token, and the full transaction

The different domain prefixes prevent either signature from being replayed in the other's context. The protocol validates both and charges the fee payer.

How this differs from EIP-4337

On Ethereum, gasless transactions require the EIP-4337 stack: a smart contract wallet, a Paymaster contract (with staked ETH), a bundler to submit UserOperations, and an EntryPoint contract. The user's account must be a contract account, not an EOA.

On Tempo, fee sponsorship works with standard EOA accounts. The user doesn't need a smart contract wallet. The fee payer doesn't need to deploy or stake anything. A sponsored transaction is a single transaction with two signatures, at the same gas cost as an unsponsored one, minus the overhead of Paymaster verification.

Cost

A standard TIP-20 transfer costs approximately 0.1 cent at base fee. Sponsoring 10,000 transfers costs about $10. The fee payer chooses which stablecoin to pay in.

Testing fee sponsorship

Moderato provides a public sponsor service at https://sponsor.moderato.tempo.xyz. Use viem's withFeePayer transport to route sponsored transactions:

import { createWalletClient, http } from "viem";
import { tempoTestnet } from "viem/chains";
import { withFeePayer } from "viem/tempo";
 
const client = createWalletClient({
  chain: tempoTestnet,
  transport: withFeePayer(
    http(),
    http("https://sponsor.moderato.tempo.xyz")
  ),
});

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