CATS is described as 'Create candidate statuses and trigger automated actions like emails, event invites, and more. Create and customize statuses to reflect your hiring process, and easily map them to report on the big picture'. There are more than 10 alternatives to CATS, not only websites but also apps for a variety of platforms, including Android, iPhone, Windows and SaaS. The best alternative is Recruitee. It's not free, so if you're looking for a free alternative, you could try Greenhouse or OpenCATS. Other great sites and apps similar to CATS are OneJobSlot (Paid), Jobvite (Paid), Crelate (Paid) and TalentLyft (Paid).
OpenCATS is a free and open-source Applicant Tracking System (ATS). Designed for Recruiters by the recruiting community for anyone who needs to manage the recruitment process from job posting, candidate application, through to candidate selection and submission.