Transactions

Gas Sponsorship Policies

Sponsorship policies are a way to control the execution of sponsored transactions on your account.

You can use them to:

• Set global spend limits.
• Restrict sponsorship to a particular chain.
• Restrict sponsorship to a particular contract.
• Allow/Disallow specific wallets
• Setup your own server verifier.

These policies can be set from your project dashboard, under project > account abstraction > settings.

The most flexible and powerful way to control the execution of sponsored transactions is to setup your own server verifier.

In the project dashboard, under project > account abstraction > settings, setup your backend URL and any additional headers you need to pass to the verifier.

On every user transaction, your backend will be called with the transaction data and the user's wallet address, your endpoint should return a boolean indicating whether the transaction should be sponsored.

Your backend will be called with the following request:

POST https://your-backend-url/verify-transaction
Content-Type: application/json
Referer: "https://api.thirdweb.com",
# additional custom headers
 
# request body
{
  "clientId": string;
  "chainId": number;
  "userOp": {
    sender: string;
    targets: string[];
    gasLimit: string;
    gasPrice: string;
    data?: {
      targets: string[];
      callDatas: string[];
      values: string[];
    };
  }
}

Your backend should process the request, apply your own policy logic based on the request data and return the following JSON response:

HTTP/1.1 200 OK
Content-Type: application/json
 
{
  "isAllowed": boolean;
  "reason"?: string;
}

The isAllowed field indicates whether the transaction should be sponsored or not. reason is an optional field that can be used to provide a reason for the decision.