Using Bootstrap 2

The current major stable version of Bootstrap is 3, which is backwards incompatible with Bootstrap 2. Besides version 3, Flask-Bootstrap is maintained for the latest version of Bootstrap 2 (although you should not expect new features, only bug fixes).


By installing Flask-Bootstrap, you will always get the latest version, which is Bootstrap 3. To install (or keep) Flask-Bootstrap 2, you will have to specify the version in your or requirements.txt similiar to this:

# other stuff in
install_requires=['flask-bootstrap<3', 'another_package']

It’s not a bad idea to pin to a specific Flask-Bootstrap version (e.g. 'flask-bootstrap==' to avoid surprises in production).


Before version 3, Flask-Bootstrap only had a README file as documentation. You can find the full file below.

You can also find previous version tags on github. To have a look at the code or sample app for major version 2, take a look at


Flask-Bootstrap packages Bootstrap into an extension that mostly consists of a blueprint named ‘bootstrap’. It can also create links to serve Bootstrap from a CDN.


Here is an example:

from flask_bootstrap import Bootstrap



This makes some new templates available, mainly bootstrap_base.html and bootstrap_responsive.html. These are blank pages that include all bootstrap resources, and have predefined blocks where you can put your content. The core block to alter is body_content, otherwise see the source of the template for more possiblities.

The url-endpoint bootstrap.static is available for refering to Bootstrap resources, but usually, this isn’t needed. A bit better is using the bootstrap_find_resource template filter, which will CDN settings into account.


A few macros are available to make your life easier. These need to be imported (I recommend create your own “base.html” template that extends one of the bootstrap base templates first and including the the macros there).

An example “base.html”:

{% extends "bootstrap_responsive.html" %}
{% import "bootstrap_wtf.html" as wtf %}

The bootstrap_wtf template contains macros to help you output forms quickly. The most basic way is using them as an aid to create a form by hand:

<form class="form form-horizontal" method="post">
  {{ form.hidden_tag() }}
  {{ wtf.form_errors(form, "only") }}

  {{ wtf.horizontal_field(form.field1) }}
  {{ wtf.horizontal_field(form.field2) }}

  <div class="form-actions">
     <button name="action_save" type="submit" class="btn btn-primary">Save changes</button>

However, often you just want to get a form done quickly and have no need for intense fine-tuning:

{{ wtf.quick_form(form) }}

Configuration options

There are a few configuration options used by the templates:

Option Default  
BOOTSTRAP_USE_MINIFIED True Whether or not to use the minified versions of the css/js files.
BOOTSTRAP_JQUERY_VERSION '1' This version of jQuery is included in the template via Google CDN. Also honors BOOTSTRAP_USE_MINIFIED. Set this to None to not include jQuery at all. Note that non-minified Bootstrap resources are sometimes missing on bootstrapcdn, so it is best not to use it without turning on BOOTSTRAP_USE_MINIFIED.
BOOTSTRAP_HTML5_SHIM True Include the default IE-fixes that are usually included when using bootstrap.
BOOTSTRAP_GOOGLE_ANALYTICS_ACCOUNT None If set, include Google Analytics boilerplate using this account.
BOOTSTRAP_USE_CDN False If True, Bootstrap resources will no be served from the local app instance, but will use a Content Delivery Network instead (configured by BOOTSTRAP_CDN_BASEURL).
BOOTSTRAP_CDN_BASEURL A dictionary set up with URLs to The URLs to which Bootstrap and other filenames are appended when using a CDN.
BOOTSTRAP_CDN_PREFER_SSL True If the BOOTSTRAP_CDN_BASEURL starts with //, prepend 'https:' to it.
BOOTSTRAP_CUSTOM_CSS False If True, no Bootstrap CSS files will be loaded. Use this if you compile a custom css file that already includes bootstrap.
BOOTSTRAP_QUERYSTRING_REVVING True If True, will apppend a querystring with the current version to all static resources served locally. This ensures that upon upgrading Flask-Bootstrap, these resources are refreshed.


Either install from github using pip or from PyPI.

A note on versioning

Flask-Bootstrap tries to keep some track of Bootstrap’s releases. Versioning is usually in the form of Bootstrap version - Flask-Bootstrap iteration. For example, a version of 2.0.3-2 bundles Bootstrap version 2.0.3 and is the second release of Flask-Bootstrap containing that version.

If you need to rely on your templates not changing, simply pin the version in your


  1. Why do I have undesired auto-escapes in my template output?

    Make sure your templates end in .htm, .html, .xml or .xhtml. Flask sets the Jinja2-autoescape mode depending on the template file extension (see this StackOverflow question for more information).

    General convention in Flask applications is to name your HTML-templates .html though.

  2. How can I add custom javascript to the template?

    Use Jinja2’s super() in conjunction with the bootstrap_js_bottom block. The super-function adds the contents of a block from the parent template, that way you can even decide if you want to include it before or after jQuery/bootstrap. Example:

    {% block bootstrap_js_bottom %}
      <script src="my_app_code.js">
    {% endblock %}
  3. How do I serve the static files in deployment?

    Flask-Bootstrap is not special in the sense that it simply adds a blueprint named bootstrap. The static files map to a specific URL-prefix (per default static/bootstrap) and are served from a specific directory found in your virtualenv installation (e.g. lib/python2.7/site-packages/flask_bootstrap/static), so a traditional setup would be setting up your webserver to serve this address from the mentioned directory.

    A more elegant approach is having a cache in front of the WSGI server that respects Cache-Control headers. Per default, Flask will serve static files with an expiration time of 12 hours (you can change this value using the SEND_FILE_MAX_AGE_DEFAULT), which should be sufficient.

    For this approach nginx (or, if you prefer, Varnish) or their cloud-service based equivalents should suffice. Flask-Bootstrap supports this by offering querystring revving (see BOOTSTRAP_QUERYSTRING_REVVING) to ensure newer Bootstrap versions are served when you upgrade Flask-Bootstrap.


See Flask-Bootstrap Changelog for changes including version 2.