Yeah I would definitely be wary about this. A self-hosted option, even if not open sourced, seems like a no-brainer to me. Nothing wrong with providing it as a SaaS as well.

Also being in the EU the first thing I look at is where the company is based and/or where they host my data, but I've trawled through this site and cannot seem to find a company address anywhere or details of their hosting setup? Nor is there a single "Security" page which outlines their credentials and security measures. I feel like these are critically important for a business like this which needs to build trust with potential customers.

The website design looks superb though and the product is definitely interesting.

EDIT: Ah noticed on the jobs page that they're in Ireland, but looks like their app front-end is hosted on Vercel and (per below) backend on AWS.

EDIT: And further confusion from the "Evervault Inc" in the footer and "Evervault Ltd" on Privacy Policy page. I'm not clear if this is an Irish company (and therefore covered by EU law) or a US company? These details are important for potential European customers.