If you got hit by a bus, your family couldn't access anything
“My spouse doesn't know what accounts we even have. If I died tomorrow she'd be locked out of the mortgage, the utilities, the photos — everything is behind my email and my 2FA.”— Hacker News ↗
Password managers store credentials but don't answer 'what accounts exist and what should happen to each'; dedicated services (Everplans) are subscription vaults that ask you to trust a startup with literally everything. The trust-shaped gap: a local-first, client-side-encrypted 'emergency binder' builder where no server ever sees the contents.
Anyone whose household finances live behind one person's logins
Build a digital 'emergency binder' builder in Next.js — everything stays client-side. A guided interview collects an account inventory (banks, utilities, subscriptions, devices), key contacts, and instructions; encrypt with a passphrase via WebCrypto and export a single encrypted file plus a printable one-page 'how to open this' sheet for family. First 3 steps: (1) the binder schema + multi-step guided form (localStorage drafts), (2) WebCrypto encrypt/decrypt round-trip with passphrase derivation (PBKDF2/Argon2), (3) export/import of the encrypted blob + a print stylesheet. Never POST binder contents anywhere.