Drop in a passport, payslip or bank statement and Cachety tiles a diagonal watermark across it, such as “Rental application, Martin Lettings, 11/10/2026”, so a leaked copy can only ever be used for that one purpose. It also blacks out fields for real, strips metadata and photo GPS, and can lock the PDF with AES-256. Everything runs in the browser, and the page’s content-security policy blocks outside connections. AGPL.