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Please note that zkApp programmability is not yet available on Mina Mainnet, but zkApps can now be deployed to Berkeley Testnet.

How to Write a zkApp

A zkApp consists of a smart contract and a UI to interact with it.

Write your smart contract using the Mina zkApp CLI.

First, install the Mina zkApp CLI.

The Mina zkApp CLI makes it easy to follow recommended best practices by providing project scaffolding including dependencies such as SnarkyJS, a test framework Jest, code auto-formatting Prettier, linting ES Lint, and more.

Install Mina zkApp CLI​

npm install -g zkapp-cli

Dependencies:

  • NodeJS 16+ (or 14 using node --experimental-wasm-threads)
  • NPM 6+
  • Git 2+

If you have a later version installed, install the required version using the package manager for your system:

  • MacOs Homebrew

  • Windows Chocolatey

  • Linux (apt, yum, and others)

    As recommended by the Node.js project, you might need to install a recent Node.js version using NodeSource binary distributions: Debian, rpm.

Start a project​

Now that you have the Mina zkApp CLI installed, you can start with an example or start your own project.

Example projects do not create an accompanying UI.

Examples are based on the standard project structure and provide additional files in the /src directory.

  1. Create the example project: zk example

    The zk example command prompts you to select an example project:

    ? Choose an example …
    ❯ sudoku
    tictactoe

    Select the sudoku example project.

    The created project includes the example files (the smart contract) in the project's src/ directory.

    To see the files that were created, change to the sudoku directory and run the ls command or open the directory in a code editor, such as VS Code.

  2. Run tests and see the tests pass: npm run test

    To rerun tests automatically when you save changes to your code, run the tests in watch mode with npm run testw.

  3. Build the example: npm run build

    Compile your TypeScript into JavaScript in the project /build directory.

  4. Configure your zkApp: zk config

    The command prompts guide you to add a deploy alias to your project config.json file. The deploy alias can be anything you want. For this example, use berkeley.

    For Berkeley Testnet, use:

    • name: berkeley
    • Mina GraphQL API URL: https://proxy.berkeley.minaexplorer.com/graphql
    • transaction fee: 0.1

  5. Fund your fee payer account.

    Follow the prompts to request tMINA.

  6. Deploy to Testnet: zk deploy

    Follow the prompts. For details, see how to deploy a zkApp.

Option B: Start your own project​

  1. Create your own project: zk project <myproj>

    The created project includes the files (the smart contract) in the project's src/ directory.

  2. Select an accompanying UI framework, if any:

    ? Create an accompanying UI project too? …
    ❯ next
    svelte
    nuxt
    empty
    none

    For your selected UI framework, follow the prompts.

    To see the files that were created, change to the project (whatever you called <myproj>) directory and run the ls command or open the directory in a code editor, such as VS Code.

  3. Run tests and see the tests pass: npm run test

    To rerun tests automatically when you save changes to your code, run the tests in watch mode with npm run testw.

  4. Build the example: npm run build

    Compile your TypeScript into JavaScript in the project /build directory.

  5. Configure your zkApp: zk config

    The command prompts guide you to add a deploy alias to your project config.json file. The deploy alias can be anything you want. For this example, use berkeley.

    For Berkeley Testnet, use:

    • name: berkeley
    • Mina GraphQL API URL: https://proxy.berkeley.minaexplorer.com/graphql
    • transaction fee: 0.1

  6. Fund your fee payer account.

    Follow the prompts to request tMina.

  7. Deploy to Testnet: zk deploy

    Follow the prompts. For details, see how to deploy a zkApp.

Writing your smart contract​

zkApps are written in TypeScript using SnarkyJS. SnarkyJS is a TypeScript library for writing smart contracts based on zero-knowledge proofs for the Mina Protocol. It is included automatically when creating a new project using the Mina zkApp CLI.

To get started writing zkApps, begin with these SnarkyJS docs:

For guided steps to create your first zkApp, start with Tutorial 1: Hello World.

For comprehensive details about the SnarkyJS API, see the SnarkyJS reference.

Next Steps​

Now that you've learned how to write and operate a basic smart contract, you can learn how to test your zkApp.