CertainKey is Bitcoin-only and focused on providing comprehensive, hands-on key audits and balance attestations for multisignature wallets.
Unlike other services that broadly cater to a range of digital assets or focus solely on custody solutions, CertainKey’s strength is its personalized, audit-driven approach for ensuring that designated custodians retain control over their Bitcoin keys—without requiring full custodial trust in third parties.
https://certainkey.gatekeeper.beauty/