This extension adds a toolbar overlay to Flask applications containing useful information for debugging.

Installing is simple with pip :

Setting up the debug toolbar is simple:

from flask import Flask from flask_debugtoolbar import DebugToolbarExtension app = Flask ( __name__ ) # the toolbar is only enabled in debug mode: app . debug = True # set a 'SECRET_KEY' to enable the Flask session cookies app . config [ 'SECRET_KEY' ] = '<replace with a secret key>' toolbar = DebugToolbarExtension ( app )

The toolbar will automatically be injected into HTML responses when debug mode is on. In production, setting app.debug = False will disable the toolbar.

This extension also supports the Flask app factory pattern by separately creating the toolbar and later initializing it for an app: