Flask is a small but powerful web development framework for Python. Though Flask is termed a micro-framework, it is no way lacking in functionality; there are many extensions available to Flask which helps it to function at the same level as other large frameworks such as Django and Ruby on Rails. This book will demonstrate how to develop a series of web application projects with the Python web micro-framework, and leverage extensions and external Python libraries and APIs to extend the development of a variety of larger and more complex web applications. The book will start by explaining Python’s Virtualenv library and how to create and switch between multiple virtual environments. You’ll first build an SQL database-backed application, which will use Flask-WTF, Flask-SQLAlchemy, Jinja templates, and other methods. Next you’ll move on to a timeline application, built using concepts including pytest-Flask, the Blinker package, data modelling for user timelines, exception handling, and creating and organizing CLI tools. Moving on, you’ll discover how to implement a photo timeline application where you’ll explore topics such as writing and running celery tasks, API error handling and testing, and Werkzeug middlewares. Finally, the book walks you through creating an application which fetches data from GitHub and stores it locally. You will also learn how to install and configure Flask-Click extension.