Staff Backend Engineer

The Vault is an MPC-based crypto custody platform for institutional and retail clients, running threshold signing across HSM and Ledger hardware. We're scaling toward Series A, launching our productized platform in 2026, and publishing original cryptographic research alongside the product. We're hiring a Staff Engineer to design and ship the custody platform's hardest backend code. This is a hands-on IC role with real technical leadership — no people management — where you drive non-trivial ini…