> ## Documentation Index
> Fetch the complete documentation index at: https://upstash.com/docs/llms.txt
> Use this file to discover all available pages before exploring further.

# Flask

<Snippet file="redis/start-redis-snippet.mdx" />

### Introduction

In this quickstart tutorial, we will explore how to use Flask with Upstash Redis to build a simple web application that increments a counter each time a user accesses the homepage.

### Environment Setup

First, install Flask and the Upstash Redis client for Python.

```shell theme={"system"}
pip install flask
pip install upstash-redis
```

### Database Setup

Create a Redis database using [Upstash Console](https://console.upstash.com) or [Upstash CLI](https://github.com/upstash/cli) and export the `UPSTASH_REDIS_REST_URL` and `UPSTASH_REDIS_REST_TOKEN` to your environment.

```shell theme={"system"}
export UPSTASH_REDIS_REST_URL=<YOUR_URL>
export UPSTASH_REDIS_REST_TOKEN=<YOUR_TOKEN>
```

You can also use `python-dotenv` to load environment variables from your `.env` file.

### Application Setup

Create `app.py`:

```py app.py theme={"system"}
from flask import Flask
from upstash_redis import Redis

app = Flask(__name__)

redis = Redis.from_env()

@app.route('/')
def index():
    count = redis.incr('counter')
    return f'Page visited {count} times.'

if __name__ == '__main__':
    app.run(debug=True)
```

### Running the Application

Run the Flask app locally:

```shell theme={"system"}
python app.py
```

Visit `http://127.0.0.1:5000/` in your browser, and you will see the `counter` increment with each refresh.

Code Breakdown

1. **Redis Setup:** We first import Flask and the Upstash Redis client. Using `Redis.from_env()`, we initialize the connection to our Redis database using the environment variables exported earlier.
2. **Increment Counter:** Each time the root route (`/`) is accessed, Redis increments the `counter` key. This key-value pair is automatically created in Redis if it does not exist, and its value is incremented on each request.
3. **Display the Count:** The number of visits is returned in the response as plain text.