Waitress is a pure Python WSGI server.

  • It is easy to configure.

  • It supports Windows directly.

  • It is easy to install as it does not require additional dependencies or compilation.

  • It does not support streaming requests, full request data is always buffered.

  • It uses a single process with multiple thread workers.

This page outlines the basics of running Waitress. Be sure to read its documentation and waitress-serve --help to understand what features are available.


Create a virtualenv, install your application, then install waitress.

$ cd hello-app
$ python -m venv .venv
$ . .venv/bin/activate
$ pip install .  # install your application
$ pip install waitress


The only required argument to waitress-serve tells it how to load your Flask application. The syntax is {module}:{app}. module is the dotted import name to the module with your application. app is the variable with the application. If you’re using the app factory pattern, use --call {module}:{factory} instead.

# equivalent to 'from hello import app'
$ waitress-serve --host hello:app

# equivalent to 'from hello import create_app; create_app()'
$ waitress-serve --host --call hello:create_app

Serving on

The --host option binds the server to local only.

Logs for each request aren’t shown, only errors are shown. Logging can be configured through the Python interface instead of the command line.

Binding Externally

Waitress should not be run as root because it would cause your application code to run as root, which is not secure. However, this means it will not be possible to bind to port 80 or 443. Instead, a reverse proxy such as nginx or Apache httpd should be used in front of Waitress.

You can bind to all external IPs on a non-privileged port by not specifying the --host option. Don’t do this when using a revers proxy setup, otherwise it will be possible to bypass the proxy. is not a valid address to navigate to, you’d use a specific IP address in your browser.