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Set up your development environment

Before you can build an app, you need the right tools in place—think of this as setting up your workshop before you start building. This tutorial walks you through installing the tools you need to run, modify, and extend the Hello World app.

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What you learn here: How to install the three tools that the Quickstart uses. By the end, your environment is ready to clone, run, and extend the Hello World app.

Follow each section in order. This tutorial explains what each piece does and why you need it—by the end, everything is in place for the next tutorial.

Prerequisites​

You need three tools before you can start:

Git

Git

Used to clone the Hello World repo. Most systems have it pre-installed.

uv

uv 0.7.3+

Installs dependencies and runs the app. Also manages the Python toolchain for you — no separate Python install needed.

Pkl

Pkl CLI

Used in Build your first app to regenerate the app's input schema after editing contract/app.pkl. Not needed to run the app.

Prepare your environment​

Verify Git​

Git is a version control system you need to download sample applications and manage your code. Most systems have Git pre-installed, but first verify it's available:

  • Check if Git is already installed: Run this command in your terminal:

    git --version

  • If Git isn't installed, download and install it from git-scm.com for your operating system.

With Git ready, you can now install the other development tools.

Install tools​

The install varies by operating system—choose your platform below and follow the steps in order. This usually takes a few minutes depending on your internet connection. Getting this foundation right means you can focus on the fun part: building your first app.

Your Mac needs these tools installed in a specific order. Follow the sequence exactly as shown.

  1. Install Homebrew: The package manager for macOS—makes installing everything else a single command.

    /bin/bash -c "$(curl -fsSL https://raw.githubusercontent.com/Homebrew/install/HEAD/install.sh)"

    Follow any post-installation instructions printed in your terminal.

  2. Install uv: Manages dependencies and runs project scripts. Also downloads and manages Python for you.

    brew install uv

  3. Install Pkl CLI: Needed to regenerate the app's input schema in Build your first app.

    brew install pkl

Verify your environment​

Open your terminal (or Command Prompt on Windows) and run these commands to confirm each tool is installed. Seeing a version number means it's ready.

  • Check uv:

    uv --version

  • Check Pkl:

    pkl --version

Something not working? If any command fails or shows an error, review the install steps for your operating system. Don't continue until all commands work properly.

What about Python? uv automatically downloads and manages Python when you install project dependencies in the next tutorial — no separate Python install needed.

If all commands showed version numbers, your environment is ready.

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Congratulations! Setting up a development environment can feel like a lot of steps, but you're through it. Your machine is ready to clone, run, and extend the Hello World app.

What's next​

Your environment is set up and ready.

Next tutorial: Run your first sample app: clone the Hello World app, run it in two commands, and read the code to understand how it works.