Flask Website Templates - Open-Source and Free

This article presents a short and comprehensive introduction to Flask and a curated list with Flask Templates provided with basic modules, database, ORM and deployment scrips on top of modern UI Kits.

The hero section provided by Material Kit 2, an open-source Flask Website Template
Material Kit 2 - Open-Source Flask Website Template

This article presents a short and comprehensive introduction to Flask and a curated list with Flask Website Templates provided with basic modules, database, ORM, and deployment scrips on top of modern UI Kits. All templates are actively versioned and supported via Github (issues tracker) and Discord - LIVE Service. For newcomers, Flask is a popular web framework written in Python actively supported by an impressive open-source community.

Topics covered in this article:
  • πŸ‘‰ What is Flask
  • πŸ‘‰ How to get started with Flask
  • πŸ‘‰ Flask - a super simple application
  • πŸ‘‰ Flask Template System - Jinja Template engine

GIF animated presentation of Material Kit 2, an open-source Flask Website Template.
Flask Material Kit 2 - Open-Source Website Template

✨ What is Flask

Flask is a lightweight WSGI web application framework. It is designed to make getting started quick and easy, with the ability to scale up to complex applications. Classified as a microframework, Flask is written in Python and it does not require particular tools or libraries. It has no database abstraction layer, form validation, or any other components where pre-existing third-party libraries provide common functions.

If we have Python installed we can see Flask in action on our browser in less than one minute. Let's make a short test:

#1 - Install Flask

$ pip install Flask

#2 - Use your preferred editor to code a minimal Flask app

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello():
    return f'Hello from Flask!'

Save the file and ...

#3 - Start the app and see it in the browser

$ env FLASK_APP=hello.py flask run
 * Serving Flask app "hello"
 * Running on http://127.0.0.1:5000/

By visiting the app in the browser we should see that warm message.


✨ Flask - More than "Hello World"

With Flask we can easily code a simple, multi-page website using a Bootstrap template. Our next sample will be coded on top of Pixel UI Kit - Β an open-source accessibility first design.

Please find below a possible codebase structure for our project. I said "possible" because Flask is highly configurable and empowers the developer with the freedom to structure the app without any constraints.

< PROJECT ROOT >
    |
    |--- app/__init__.py
    |--- app/
    |     | --- <static/assets>
    |     |       |--- <css>
    |     |       |--- <Js>
    |     |       |--- <img>
    |     |
    |     | --- <templates>
    |             |---<includes>                   # Page chunks, components
    |             |     | --- navigation.html      # Top bar
    |             |     | --- sidebar.html         # Left sidebar
    |             |     | --- scripts.html         # JS scripts common to al
    |             |     | --- footer.html          # The common footer
    |             |
    |             |---<layouts>                    # App Layouts
    |             |
    |          index.html                          # The default page
    |          *.html                              # All other pages 
    |
    |--- requirements.txt
    |
    |--- run.py
    |
    |-----------------------------

Let's iterate over the relevant files:

  • run.py - the entry point used to start the application
  • requirements.txt - a file that specify all dependencies (for now is just Flask)
  • app - the application folder where we will add our code
  • app/__init__.py - This file is required to let us use the app as a Python Package
  • app/static - this folder will contain design assets: JS, css and images.
  • templates - the directory with pages, layouts and components used by Flask to generate some nice pages for us

Before we start using templates in Flask, let's code a simple app that use strings to render a page:

from flask import Flask

app = Flask(__name__)

@app.route('/')
def hello():
    return '''
<html> 
    <head> 
      <title>Simple App</title> 
     </head> 
      <body> 
        <h1>Hello</h1> 
        <p>From Flask - no templates</p> 
      </body> 
</html>'''

Basically we are returning a string formatted as a simple HTML page with all standard sections (HEAD, body tags). If the project should render more than one line on every page, it might be a good idea to start using a template system to have a well organized project, easy to maintain and use by us and others.


✨ Jinja Template System

What is Jinja - Jinja is a library for Python used by popular web frameworks like Flask and Django to serve HTML pages in a secure and efficient way. Using a template engine is a common practice in web development, no matter the language or framework used to code the web application.

How to install Jinja
$ pip install jinja2

We can test and play with the Jinja Engine directly in the Python console:

>>> from jinja2 import Template
>>> t = Template("Jinja {{ token }}!")
>>> t.render(token="works")
u'Jinja works!'

Jinja Template System - A few reasons to use it

Work less

Jinja allows us to reuse components (aka common HTML chunks) in many pages and contexts with minor changes. Imagine that we have a footer with some links and contact information, common to all pages in a web application. Using Jinja we can define a separate file named footer.html and we can reuse it with a simple include:

footer.html definition

<footer class="footer">
    <div class=" container-fluid ">
        <span>
            &copy; YourCompany;
        </span>

        <span>
            Contact: bill [ @ ] microsoft.com
        </span>
    </div>
</footer>

footer.html usage in a final page:

<head>
  <title>
    Jinja Template - Cheat Sheet | Dev.to
  </title>
</head>
<body>
    <div class="content">
        Some cool content
    </div>

    <!-- The magic include line --> 
    {% include 'footer.html' %}    

</body>
</html>

Template Inheritance

Inheritance, in the Jinja Context, means to define a base template that defines the basic structure of all subsequent child templates. This master template can be inherited via extends directive to build variations (new pages).

A real sample

Parent HTML - saved as base.html

<html>
  <head>
    <title>My Jinja {% block title %}{% endblock %} </title>
  </head>
  <body>
    <div class="container">
      <h2>This is from the base template</h2>
      <br>
      { block content }{ endblock }
      <br>
    </div>
  </body>
</html>

The Child template - saved as child.html

{ extends "base.html" }

{ block title } MySample { endblock }

{ block content }
  Cool content here
{ endblock }

When Jinja loads child.html, the { extends } block informs the engine to merge the base.html template with the content provided by child.html.

  • { block title } becomes MySample
  • { block content } becomes Cool content here

Generated HTML (by Jinja)

<html>
  <head>
    <title>My Jinja MySample</title>
  </head>
  <body>
    <div class="container">
      <h2>This is from the base template</h2>
      <br>
      Cool content here
      <br>
    </div>
  </body>
</html>

Jinja - Render Lists

Jinja supports control structures like if/else, for loops to manipulate lists and dictionaries.

List definition

# Define a simple list
users = ['user1','user2', 'user3']

Jinja code snippet (aka Flask template)

<h1>Members</h1>
<ul>
{% for user in users %}
  <li>{{ user }}</li>
{% endfor %}
</ul>

Generated HTML

<h1>Members</h1>
<ul>
  <li>user1</li>
  <li>user2</li>
  <li>user3</li>
</ul>

Jinja Filters

Filter sections allow to apply regular Jinja filters on a block of template data - the syntax:

Jinja code snippet

{% filter upper %}
    uppercase me
{% endfilter %}

Generated HTML

UPPERCASE ME

Jinja Math

Jinja allows you to compute values. Here are some samples:

{{ 1 + 1 }} will render 1
{{ 1 / 2 }} will render 0.5
{{ 11 % 7 }} will render 4

Jinja comes with many features and the above presentation is just a small part of the whole story. Using a template engine, once we are getting familiar with it, can help us to win time, work less and reuse previous work.

In the next section, we will present a few development-ready Flask Templates released under permissive licenses and suitable for hobby & commercial projects.


✨ Flask Template - Pixel UI

Pixel UI Kit (Free version) designed by Themesberg and coded in Flask Framework with SQLite database, SqlAlchemy ORM, and authentication.

Pixel is a free, fully responsive, and modern Bootstrap 4 UI Kit that will help you build creative and professional websites. Use our components and sections, switch some Sass variables to build and arrange pages to best suit your needs.

Pixel Lite UI - Flask Website Template.
Pixel Lite UI - Flask Website Template.

✨ Flask Template Datta Able

Datta Able Free Dashboard designed by CodedThemes coded in Flask Framework with SQLite database, SQLAlchemy ORM and authentication.

Datta Able Bootstrap Lite is the most stylised Bootstrap 4 Lite Admin Template, around all other Lite/Free admin templates in the market. It comes with high feature-rich pages and components with fully developer-centric code. Before developing Datta Able our key points were performance and design.

Datta Able - Flask Website Template.
Datta Able - Flask Website Template.

✨ Flask Template Argon

Argon Dashboard designed by Creative-Tim coded in Flask with authentication, ORM, Blueprints, deployment scripts for Docker, HEROKU, and Gunicorn/Nginx stack.

Argon Dashboard is built with over 100 individual components, giving you the freedom of choosing and combining. Every component has multiple states for colors, styles, hover, focus, that you can easily access and use.

Argon Dashboard - Flask Website Template.
Argon Dashboard - Flask Website Template.

✨ Flask Template Volt

Volt Admin Dashboard (free version) designed by Themesberg and coded in Flask Framework with SQLite database, SqlAlchemy ORM and authentication.

Volt Dashboard is a free and open-source Bootstrap 5 Admin Dashboard featuring over 100 components, 11 example pages, and 3 plugins with Vanilla JS. There are more than 100 free Bootstrap 5 components included some of them being buttons, alerts, modals, date pickers and so on.

Volt Dashboard - Flask Website Template.
Volt Dashboard - Flask Website Template.

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