Building a modular testable and scalable app is no small task. Businesses that utilize web applications need to avoid congestion as their customer base grows from a few buyers to millions of visitors which affects app functionality. Scalability is the ability to maintain functionality and data consistency when millions of users are concurrently interacting with an app. The Python programming language offers a robust framework that helps you deploy scalable applications. This course presents an intermediate-to-advanced level approach for web programmers who are already familiar with Python and Flask.We begin by analyzing vital areas that involve building scalable web applications with MongoDB and the Flask framework. We will outline the encapsulation task distribution and data sharding features of MongoDB that help you scale horizontally. Next we introduce Cloud9IDE. You will learn to use Cloud9 to test a database and install a virtual environment for Python code development. Then step-by-step we will build a social web app with the same architectural modularity and scalability as Twitter.We present the model best practices for building user registration forms registrant validation user profiles and unit testing interfaces with Flask Blueprint. You will learn how to set up Amazon AWS for email processing and image hosting. Finally we will examine the relationship and feed model designs which include adding profile images reusable follow buttons feed templates and feed comments with image support to your dummy social web app. This advanced course will teach you how to build modular testable and scalable web applications with MongoDB and Flask Blueprint. Do not delay. Start learning today!