Frozen-Flask

1.0.2 verified Mon Apr 27 auth: no python

Freezes a Flask application into a set of static files. Version 1.0.2 is current (released 2024) and supports Python >=3.8 with Flask 2 and 3. The library follows a stable release cadence.

pip install frozen-flask

Common errors

error ModuleNotFoundError: No module named 'flask_frozen' ↓

cause Installed frozen-flask but imported with wrong name.

fix

Use 'from flask_frozen import Freezer'. Package name is frozen-flask, module is flask_frozen.

error flask_frozen.FlaskFrozenError: No URLs found to freeze. Build will be empty. ↓

cause No routes discovered because the app doesn't expose any URLs that can be reached via GET requests.

fix

Ensure you have at least one route decorated with @app.route and that the app is properly configured.

error OSError: [Errno 2] No such file or directory: 'build/index.html' ↓

cause The freezer tried to write a file but the build directory doesn't exist.

fix

Set FREEZER_DESTINATION_DIR to an existing directory or let the freezer create it (default is 'build').

Warnings

breaking Version 1.0.0 dropped support for Python 2 and PyPy. Flask 2 and 3 only. ↓

fix Use Python >=3.8 and Flask >=2.

deprecated The `FREEZER_DESTINATION` config option is deprecated in favor of `FREEZER_DESTINATION_DIR` in some docs; check your version. ↓

fix Use `FREEZER_DESTINATION_DIR` if using Frozen-Flask 1.x.

gotcha Static files need to be included explicitly via the app's static folder or via `url_for('static', ...)` in your templates. Frozen-Flask only processes routes it discovers during crawling. ↓

fix Ensure all static assets are linked from pages that are discoverable by the freezer.

gotcha The freezer does not follow external links; if your app links to other sites, those won't be frozen. ↓

fix Use `@freezer.register_generator` to explicitly add URLs that are not discovered by crawling.

Imports

Freezer

wrong

from frozen_flask import Freezer

correct

from flask_frozen import Freezer

The package name uses underscores, not hyphens.

Quickstart

Basic usage: create a Flask app, attach Freezer, and call freeze().

from flask import Flask
from flask_frozen import Freezer

app = Flask(__name__)

@app.route('/')
def index():
    return 'Hello, world!'

freezer = Freezer(app)

if __name__ == '__main__':
    freezer.freeze()