Terms of use

Last updated: 2026-10-03.

Who's Bluffing is a free, independent, non-commercial project: a daily game, a 5-minute assessment, a classroom mode and a Slack app about how sure people are of what they know. By using it you agree to these terms. If you don't agree, please don't use it.

Free, with no accounts

Who's Bluffing costs nothing. There are no accounts, no advertising and no paid features, so there is nothing to sign up for and nothing to cancel.

Provided as is

Who's Bluffing is provided "as is", without any warranty. We try to keep every question correct and the site running, but answers can contain mistakes, and the site, the API or the Slack app may be unavailable, change or stop at any time. Scores are a game and a rough measure of calibration, not advice and not an assessment for any official purpose. As far as the law allows, the people who run Who's Bluffing are not liable for any loss that comes from using it.

Acceptable use

Please don't:

• send automated or bulk traffic, or try to overload, probe or break the site, the API or the Slack app;
• submit made-up answers or reports to distort the public numbers, the research data or the question pool;
• write personal information about anyone in the report box under a question;
• use Who's Bluffing to break the law or anyone else's rights.

We may block traffic that breaks these rules.

The API

The daily API (documented at /docs/api) exists for the Who's Bluffing web game and Slack app. If you build on it, keep request volumes low, never send personal data, and expect it to change without notice.

Your data

What is stored, why, and for how long is described in the privacy policy. Answers are anonymous and go into a public research dataset; by playing, you agree to that use.

Classes and Slack workspaces

A teacher who creates a class code, or a member who installs the Slack app, should tell their students or colleagues that answers are collected anonymously for research.

Source and licence

The source code is published on GitHub so that anyone can read it and verify the research. It is not open source: all rights are reserved, and no permission is granted to use, copy, modify or redistribute it, except to run it locally to verify published results (see the LICENSE file). Published datasets are licensed under CC BY-NC 4.0. Questions are built from Wikidata and official sources, each linked from the question.

Changes

We may update these terms. The date at the top shows the current version; using Who's Bluffing after a change means you accept it.

Contact

Questions or problems: open an issue on GitHub.

Source: TERMS.md on GitHub.