Flask is described as 'lightweight web application framework written in Python and based on the Werkzeug WSGI toolkit and Jinja2 template engine' and is an app in the Development category. There are more than 10 alternatives to Flask for a variety of platforms, including Windows, Linux, Mac, Self-Hosted solutions and Python. The best alternative is Django, which is both free and Open Source. Other great apps like Flask are ASP.NET (Free), FastAPI (Free, Open Source), Crow (Free, Open Source) and Sinatra (Free, Open Source).
Django is a high-level Python Web framework that encourages rapid development and clean, pragmatic design. Built by experienced developers, it takes care of much of the hassle of Web development, so you can focus on writing your app without needing to reinvent the wheel.
Crow is a C++ microframework for running web services. It uses routing similar to Python's Flask which makes it easy to use. It is also extremely fast, beating multiple existing C++ frameworks as well as non C++ frameworks. Features
Sinatra is a free and open source software web application library and domain-specific language written in Ruby. It is an alternative to other Ruby web application frameworks such as Ruby on Rails, Merb, Nitro, Camping, and Rango. It is dependent on the Rack web server interface.
Falcon is a bare-metal Python web API framework for building very fast app backends and microservices. Organizations like LinkedIn, Leadpages, Wargaming, and Rackspace rely on Falcon for critical projects.
The jam.py is an object-oriented, event-driven framework with hierarchical structure. All this, in combination with very tight DB/GUI coupling, is the base for the DRY (don't repeat yourself) principle that is underlying the framework.
Bottle is a fast, simple and lightweight WSGI micro web-framework for Python. It is distributed as a single file module and has no dependencies other than the Python Standard Library. Routing: Requests to function-call mapping with support for clean and dynamic URLs.
ViUR – the Information System for the Google App Engine™ plattform – is a »sandbox« for designers and developers. With the help of ViUR you can easy build web applications running on Google's infrastructure.