Firefox Monitor is an online service developed by Mozilla, announced in June 2018, and launched on September 25 of that year.^[1] It informs users if their email address and passwords used have been leaked in data breaches, using the database provided by Have I Been Pwned? (HIBP). Mozilla is also working with HIBP's creator, Troy Hunt.^[1][2] Despite the name, this service is not limited to Mozilla Firefox alone, but can be accessed as a website from all common browsers.^[3]

The service partnered with OneRep as data removal from online directories and data aggregator on individuals. According to reporting by Krebs on Security, OneRep founder had founded multiple people-search companies in the past thus having a conflict of interest.^[4] Mozilla said in a statement, "We were aware of the past affiliations with the entities named in the article and were assured they had ended prior to our work together. We’re now looking into this further. We will always put the privacy and security of our customers first and will provide updates as needed.” Following up on their statement shortly after, Mozilla's vice president of communications told technology news site The Verge that it had ended the partnership with Onerep. It was not yet clear what this would mean for the Firefox Monitor Service.^[5]