Flask-Debug is an extension for Flask that displays various debugging insights during development.

from flask import Flask
from flask_debug import Debug

app = Flask(__name__)

It can be manually added but also (using Flask-Appconfig) be automatically instantiated only during development and invisible in production.

Opening http://localhost:5000/_debug will show some information about the application, such as a list of registered views, url maps or configuration values.

See the documentation for more details.