Tox has two different meanings depending on the context:

1. Tox is a command-line driven automated testing tool for Python, based on the use of virtualenv. It can be used for both manually-invoked testing from the desktop, or continuous testing within continuous integration frameworks such as Jenkins or Travis CI. Its use began to become popular in the Python community from around 2015. Tox acts a wrapper for both virtual environments and test automation tools, to simplify the consistent testing of Python code across a range of environments. It integrates the use of a virtualisation tool, such as virtualenv, with a test script such as Imprimatur. This gives a consistent container-based testing environment on both desktops and integration servers. It also allows testing in a range of Python environments, such as Python 2 or Python 3 specific contexts. Tox is configured through a simple tox.ini file in INI format).

2. Tox is a peer-to-peer instant-messaging and video-calling protocol that offers end-to-end encryption. The stated goal of the project is to provide secure communication that is not subject to surveillance or censorship. Tox is easy-to-use software that connects you with friends and family without anyone else listening in. While other big-name services require you to pay for features, Tox is completely free and comes without advertising. Tox is made by the people who use it — people fed up with the existing options that spy on us, track us, censor us, and keep us from innovating. There are no corporate interests, and no hidden agendas. Everything you do with Tox is encrypted using open-source libraries. The only people who can see your conversations are the people youre talking with. Tox has no central servers that can be raided, shut down, or forced to turn over data — the network is made up of its users.