Flask Setup for Beginners

Version: 0.17.0

When to Use

• User wants Flask web application
• Beginner needs Flask environment setup
• User asks "How do I set up Flask?"

Instructions for ASSISTANT

Format ALL instructions as Claude Code copy/paste blocks.

DO NOT: Manual instructions like "Open File Explorer", "Navigate to folder" ALWAYS: Single code block with TASK, STEPs, and report request

Setup Steps

1. Verify Python

python --version

Expected: Python 3.8+ | If missing: Install from python.org, check "Add to PATH"

2. Create Virtual Environment

python -m venv venv

What: Isolated Python environment for project Verify: venv folder created (10-30 seconds)

3. Activate Virtual Environment

Windows PowerShell: venv\Scripts\Activate.ps1 Windows CMD: venv\Scripts\activate.bat Mac/Linux: source venv/bin/activate

Success: (venv) appears in prompt Issue (Windows): Set-ExecutionPolicy -ExecutionPolicy RemoteSigned -Scope CurrentUser

4. Install Flask

pip install flask

Wait: 30-60 seconds Verify: "Successfully installed flask-X.X.X"

5. Create app.py

Location: Project root (same level as venv/)

my-project/
├── venv/
└── app.py  ← Create here

6. Verify Installation

python --version
pip list
python -c "import flask; print(flask.__version__)"

Troubleshooting

Next Steps

After setup: Create first route, run dev server, build first page.

Remember: Keep terminal with (venv) open while developing.

End of Skill