Gas Sponsorship

Gas sponsorship lets you (the custodian) pay gas fees on behalf of your users. The user's wallet signs the transaction, but the gas is covered by a Tatum-managed relayer.

How It Works

When sponsorGas: true is set:

1. The enclave constructs the transaction with an empty gas payment from the user's wallet
2. Tatum's relayer wraps it in a meta-transaction and submits it, paying the gas
3. The user's wallet signs the payload but never needs native tokens for gas

Gas sponsorship is available on EVM-compatible chains only.

Usage with sendAssets

await client.sendAssets({
  body: {
    share: shares.SECP256K1.share,
    chain: WalletChain.POLYGON_MAINNET,
    to: "0xRecipient",
    token: "0xUSDCContractAddress",
    amount: "10",
    sponsorGas: true,
  },
});

Usage with sign

await client.sign({
  body: {
    share: shares.SECP256K1.share,
    method: "eth_sendTransaction",
    params: [{ to: "0xRecipient", data: "0x...", value: "0x0" }],
    chainId: WalletChain.POLYGON_MAINNET,
    to: "0xRecipient",
    sponsorGas: true,
  },
});

When to Use

• Onboarding flows — new users who don't yet hold native tokens for gas
• Token-only wallets — users holding ERC-20/SPL tokens but no native currency
• Improved UX — hide gas complexity from end users entirely

Pre-signatures

For high-throughput flows, you can pre-compute MPC presignatures and pass them at signing time to reduce latency:

await client.sendAssets({
  body: {
    share: shares.SECP256K1.share,
    chain: WalletChain.ETHEREUM_MAINNET,
    to: "0xRecipient",
    token: "NATIVE",
    amount: "0.01",
    sponsorGas: true,
    presignature: "...",   // pre-computed presignature
    presignatureId: "...", // ID of the presignature
  },
});

Contact Tatum to enable pre-signature generation for your custodian account.