Setting up Flask locally — macOS🔖

You need to install three things. The Git step is the awkward one on Mac — read it carefully.

1. Install Python🔖

Go to python.org/downloads and download the latest Python 3 macOS installer (the .pkg file).

Run it and follow the prompts. Default options are fine.

To check it worked, open Terminal (search for it in Spotlight with Cmd+Space). Type:

python3 --version

You should see a version number like Python 3.13.x.

2. Install Git🔖

Mac does not come with Git pre-installed. The way to get it is through Apple's developer tools.

Open Terminal and type:

xcode-select --install

A dialog box will pop up asking if you want to install the Command Line Developer Tools. Click Install (not "Get Xcode" — you do not want the full Xcode app). It will download and install. This takes a few minutes on a good connection.

When it finishes, check it worked:

git --version

You should see a version number.

3. Install VS Code🔖

Go to code.visualstudio.com and download the macOS version. Open the downloaded .zip, drag Visual Studio Code into your Applications folder.

Open VS Code. Click the Extensions icon on the left sidebar (four squares). Search for Python and install the extension by Microsoft.

Connect to GitHub🔖

In VS Code, click the Source Control icon on the left sidebar (the branch icon). Click Clone Repository, then Clone from GitHub.

A browser window will open asking you to sign into GitHub. Use your school Google account. Come back to VS Code when it's done.

A dropdown shows your repos. Select the one you want to work on. When VS Code asks where to save it, Documents or Desktop is fine. Click Open when prompted.

Install Flask and run your app🔖

In VS Code, open Terminal → New Terminal.

Type this and press Enter:

pip3 install -r requirements.txt

When it finishes, type:

flask run --debug

You should see output ending in something like Running on http://127.0.0.1:5000. Open Chrome and go to localhost:5000.

The --debug flag means Flask watches your files. Every time you save app.py, the server restarts automatically — you can see it in the terminal. You do not need to stop and restart it yourself while you work.

If you get a "port already in use" error🔖

Newer versions of macOS use port 5000 for AirPlay. If Flask complains, run it on a different port:

flask run --debug --port 5001

Then go to localhost:5001 instead.

If you close the terminal or restart VS Code, run flask run --debug again. Your code is always saved separately.

Saving your work🔖

The Source Control panel works the same way it did in Codespaces:

1. Write a short message describing your change
2. Click Commit
3. Click Sync Changes

Your work is saved to GitHub.