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Step into the Paymaster Bundler experience.

Just a quick heads up: this experience is a work in progress, keep an eye out for updates as we work on making it even better!
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Guide

Paymaster & Bundler Experience

Welcome to the Paymaster & Bundler experience! This guide will help you get started with Coinbase Cloud's Paymaster.

If you haven't done so already, check the Build Onchain Apps homepage to get the repo running locally. You'll also need to complete the setup steps below to render the application locally.

1. Sign up for Coinbase Cloud and create your Base project

This example uses Coinbase Cloud's Paymaster and Bundler to sponsor transactions.

Get started with .25 ETH in free credits:
  • Navigate to the Base Node homepage
  • Sign up for a Coinbase Cloud account, if you don't have one already
  • Create a

    Base

    project under

    Start a New Project

    • Choose

      Sepolia

      as the network
  • Under Paymaster & Bundler, click

    Activate

    • This step may take up to 30 seconds to propagate changes

    • (Optional) Set a custom gas policy for your project under Manage

  • Copy your RPC URL, and set it as

    NEXT_PUBLIC_RPC_URL

    and

    NEXT_PUBLIC_PAYMASTER_URL

    in the .env file.

2. Set up your embedded wallet & signer

This example uses Privy embedded wallets for authentication and as a signer for the smart contract account.

However, you can use any other embedded wallet or signer.
  • Navigate to https://www.privy.io/
  • Create an app, copy your app ID, and set it as

    NEXT_PUBLIC_PRIVY_ID

    in the .env file.
  • You can customize the logo and name of your application in the dashboard.
  • To change the signer for the smart contract account, modify these lines in PaymasterBundlerDemo.tsx
    • javascript
    ...

3. Send your own sponsored transactions!

  • Get started by modifying ./_contracts and replacing it with the contract ABI of your choice.
  • In constants.ts, modify the

    contract_address

    environment variable.
  • In the handleOpenBox callback in Gameplay.tsx, you'll want to replace the encodeFunctionData parameters with the ABI, function name, and arguments of the contract you're calling.
    • javascript
    ...
  • To integrate with other SDKs like Alchemy or Pimlico, refer to the Coinbase Cloud example repo.