flask [wiki.Steeve.ca]

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Flask is a lightweight and flexible web application framework written in Python. Created by Armin Ronacher as part of the Pallets project, Flask is designed to be simple, unopinionated, and easy to extend—making it ideal for building APIs, microservices, and small-to-medium web applications.

Flask follows the WSGI (Web Server Gateway Interface) standard and uses Werkzeug for routing and Jinja2 as its default templating engine.

Overview

Flask is often referred to as a “micro-framework” because it does not require tools or libraries beyond what Python provides by default. However, it remains powerful and extensible, allowing developers to integrate third-party components or build their own as needed.

Flask emphasizes simplicity and developer control, following the philosophy of “doing one thing well”. It is widely used in production by tech companies and startups for REST APIs, dashboards, admin panels, and backend systems.

Key Features

Routing and URL Mapping
Flask allows developers to define routes using decorators. Each route corresponds to a Python function (view), enabling clear control over request handling.

Jinja2 Templating Engine
Jinja2 is a powerful templating system that supports template inheritance, macros, and filters, enabling separation of logic and presentation.

Built-in Development Server and Debugger
Flask includes a lightweight server for local development and a debugger with an interactive console for troubleshooting.

Request and Session Management
Flask provides request, response, and session handling through a global context and secure cookie-based sessions.

Extensions Ecosystem
A rich set of Flask extensionssupport features like:

ORM (e.g., Flask-SQLAlchemy)

Authentication (Flask-Login)

Forms (Flask-WTF)

REST APIs (Flask-RESTful)

Migrations (Flask-Migrate)

REST API Ready
Flask is commonly used to build JSON-based APIs, especially in data science and machine learning workflows.