Screening for cartels: tool for procurers

A tool to help procurers screen their tender data for signs of illegal bid-rigging activity.


Background report

Government Digital Service statement of assurance

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Cartels are illegal. They’re a form of stealing that stop businesses, consumers and taxpayers getting a fair deal.

Having a cartel in your supply chain can raise prices by 30% or more from competitive levels. Cartels operate in secret and can be difficult to spot.

The Competition and Markets Authority has produced a free tool to help spot unusual bidder behaviour and pricing patterns identified in past cartels. It will tell you which (if any) of your procurement exercises show any signs of bid-rigging.

Accessing the tool

The free tool is digitally signed with Microsoft Authenticode certification. It is available for download on GitHub, an open source development platform. To receive log in details to access the GitHub site, please email

You will be able to download the tool, where you can test your procurement data. For information on using the tool and what to do if you do spot unusual bidder behaviour in your data see ‘About the screening for cartels tool’ above.

Find out more about cartels, and how to report information to the CMA on the stop cartels page.

Published 13 July 2017
Last updated 15 December 2017 + show all updates
  1. Statement of digital quality assurance and case study added.
  2. First published.