Short version: email alerts are the only place this project stores anything personal, and it's easy to leave.
The job listings this site and Job Radar Hub serve are generic and public: title, company, location, a URL, a description. None of it is personal data, and none of it is about you.
If you sign up for email alerts, this is collected:
Signup is double opt-in: nothing is sent until you click the confirm link in the first email. Every alert email includes an unsubscribe link that works immediately, no login required. If you never confirm, the pending signup is deleted automatically after 7 days.
Alerts are sent via Resend, a transactional email provider -- your email address and saved search are shared with them only to the extent needed to deliver the message.
To have your data removed at any time, unsubscribe from the link in any alert email, or open an issue asking for it to be deleted directly.
This site measures traffic (including non-browser/agent traffic) via Google Analytics -- see this site's source for exactly how. No personal data is intentionally collected there either.