Flask – Microframework for Python based on Werkzeug, Jinja2

Flask is a micro web framework written in Python based on the Werkzeug toolkit and Jinja2 template engine. It’s mature software with development commencing in 2010. It powers some of the most popular websites.

It’s a microframework intended for getting started very quickly as there’s very little boilerplate code for writing a simple app.

Flask is not a strictly “conventional” framework and relies partly on configuration files.

Features include:

  • Contains development server and debugger. It’s recommended to use the flask command line utility; there’s also the option of using
  • Integrated support for unit testing. Flask provides a way to test your application by exposing the Werkzeug test client and handling the context locals.
  • RESTful request dispatching.
  • Uses Jinja2 as its template engine. It’s fast, widely used and secure with the optional sandboxed template execution environment. It’s modelled after Django’s templates. with the default syntax of Jinja2 matching Django syntax in many respects.
    • Sandboxed execution – used to evaluate untrusted code.
    • Powerful automatic HTML escaping system for XSS prevention.
    • Template inheritance – build a base “skeleton” template that contains all the common elements of a site and defines blocks that child templates can override.
    • Compiles down to the optimal Python code just in time.
    • Optional ahead-of-time template compilation.
    • Easy to debug. Line numbers of exceptions directly point to the correct line in the template.
    • Configurable syntax.
    • Supports extensions that can add extra filters, tests, globals or even extend the parser.
    • Integration into other tools such as frameworks, the Babel library or your favourite editor.
  • Support for secure cookies (client side sessions).
  • 100% Web Server Gateway Interface (WSGI) 1.0 compliant.
  • Totally Unicode based when it comes to text.
  • Uses thread-local objects internally.
  • Flask-Login is an extension which allows you to integrate authentication system into your Flask application easily.
  • Pluggable views – create views in the form of classes instead of normally as functions.
  • Extensive documentation.
  • Built-in integration of the click command line interface.
  • Google App Engine compatibility.
  • Many extensions are available that make adding new functionality easy.

Support: GitHub Code Repository, Documentation, Flask Extensions
Developer: Armin Ronacher and contributors
License: BSD License

Flask is written in Python. Learn Python with our recommended free books and free tutorials.

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