Custis by Unity Nodes

Custis is a self-custodial wallet on Canton Network. This extension does one thing: it lets websites find it, by adding window.canton to the page.
It holds no keys and cannot see them. When a site asks for a signature, a real wallet window opens at custis.unitynodes.com - with the address visible in the browser bar - and the person decides there.

The extension has no permissions, no storage and no background script. Its entire source is one 8 KB file, shipped unminified.
The signing key is derived from a passkey in the wallet on its own domain.
That is deliberate: inside an extension the WebAuthn RP ID equals the
extension's own id, which depends on the store's signing key - so changing
stores would mean losing access to the account.