This document describes how to prepare for and install Toil. Note that Toil requires that the user run all commands inside of a Python virtualenv. Instructions for installing and creating a Python virtual environment are provided below.

Preparing Your Python Runtime Environment

Toil currently supports Python 3.7, 3.8, 3.9, and 3.10, and requires a virtualenv to be active to install.

If not already present, please install the latest Python virtualenv using pip:

$ sudo pip install virtualenv

And create a virtual environment called venv in your home directory:

$ virtualenv ~/venv

If the user does not have root privileges, there are a few more steps, but one can download a specific virtualenv package directly, untar the file, create, and source the virtualenv (version 15.1.0 as an example) using

$ curl -O
$ tar xvfz virtualenv-15.1.0.tar.gz
$ cd virtualenv-15.1.0
$ python ~/venv

Now that you’ve created your virtualenv, activate your virtual environment:

$ source ~/venv/bin/activate

Basic Installation

If you need only the basic version of Toil, it can be easily installed using pip:

$ pip install toil

Now you’re ready to run your first Toil workflow!

(If you need any of the extra features don’t do this yet and instead skip to the next section.)

Installing Toil with Extra Features

Python headers and static libraries

Needed for the mesos, aws, google, and encryption extras.

On Ubuntu:

$ sudo apt-get install build-essential python-dev

On macOS:

$ xcode-select --install

Encryption specific headers and library

Needed for the encryption extra.

On Ubuntu:

$ sudo apt-get install libssl-dev libffi-dev

On macOS:

$ brew install libssl libffi

Or see Cryptography for other systems.

Some optional features, called extras, are not included in the basic installation of Toil. To install Toil with all its bells and whistles, first install any necessary headers and libraries (python-dev, libffi-dev). Then run

$ pip install toil[aws,google,mesos,encryption,cwl,wdl,kubernetes,server]


$ pip install toil[all]

Here’s what each extra provides:

Extra Description
all Installs all extras (though htcondor is linux-only and will be skipped if not on a linux computer).
aws Provides support for managing a cluster on Amazon Web Service (AWS) using Toil’s built in Cluster Utilities. Clusters can scale up and down automatically. It also supports storing workflow state.
google Experimental. Stores workflow state in Google Cloud Storage.

Provides support for running Toil on an Apache Mesos cluster. Note that running Toil on other batch systems does not require an extra. The mesos extra requires the following native dependencies:


If launching toil remotely on a mesos instance, to install Toil with the mesos extra in a virtualenv, be sure to create that virtualenv with the --system-site-packages flag (only use remotely!):

$ virtualenv ~/venv --system-site-packages

Otherwise, you’ll see something like this:

ImportError: No module named mesos.native
htcondor Support for the htcondor batch system. This currently is a linux only extra.

Provides client-side encryption for files stored in the AWS job store. This extra requires the following native dependencies:

cwl Provides support for running workflows written using the Common Workflow Language.
wdl Provides support for running workflows written using the Workflow Description Language. This extra has no native dependencies.
kubernetes Provides support for running workflows written using a Kubernetes cluster.
server Provides support for Toil server mode, including support for the GA4GH Workflow Execution Service API.

Building from Source

If developing with Toil, you will need to build from source. This allows changes you make to Toil to be reflected immediately in your runtime environment.

First, clone the source:

$ git clone
$ cd toil

Then, create and activate a virtualenv:

$ virtualenv venv
$ . venv/bin/activate

From there, you can list all available Make targets by running make. First and foremost, we want to install Toil’s build requirements (these are additional packages that Toil needs to be tested and built but not to be run):

$ make prepare

Now, we can install Toil in development mode (such that changes to the source code will immediately affect the virtualenv):

$ make develop

Or, to install with support for all optional Installing Toil with Extra Features:

$ make develop extras=[aws,mesos,google,encryption,cwl]


$ make develop extras=[all]

To build the docs, run make develop with all extras followed by

$ make docs

To run a quick batch of tests (this should take less than 30 minutes) run

$ export TOIL_TEST_QUICK=True; make test

For more information on testing see Running Tests.