Linky

⚠️ Hobby tool without any guarantees. Use at your own risk.

Linky is a simple mobile-first PWA for managing contacts, messaging via Nostr, and sending Lightning payments using Cashu tokens. It is local-first: your data is stored locally and the app works offline.

Used protocols

• nostr - communication
• evolu - data storage
• cashu, mints - lightning integration
• npub.cash - lightning address management
• credo - promises - for details see Credo.md

How it works

• You can either use existing nsec or Create account - Linky generates a nostr identity nsec/npub key pair

• nsec is used for:

  • derivation of seed - 12 words (BIP39)
  • selection of default name and avatar
  • profile management - photo, name, lightning address
  • sending encrypted and private messages - gift-wrapped (NIP17)
  • registering lightning address on npub.cash
  • managing main cashu mint on npub.cash
  • collecting cashu tokens from npub.cash
  • issuing own credo tokens

• seed is used for:

  • authentication against evolu servers
  • cashu token requests and token restoration

• Evolu is used for local-first data storage and synchronization between devices.

  • Contacts (npub, name, lightning address, group)
  • Cashu tokens (token, status)
  • Credo tokens (emitted, received)
  • Main mint

Feature set

• Contacts
  • Scan, add, edit contacts
  • Share your profile (npub) including name, photo, and lightning address
• Messages
  • Encrypted private chat via Nostr (NIP-17)
  • Cashu and Credo tokens are rendered as pills in chat
• Wallet
  • Paste and store Cashu tokens
  • Balance shows only Cashu; Credo promises are listed separately
• Payments
  • Pay to contact
    • Lightning if selected or if Cashu/Credo message payment isn’t available
    • Cashu/Credo message payment: consume Credo owed to you first, then Cashu, then (optionally) issue a Credo promise for the remainder
  • Credo promises are capped (100,000 sat) and expire in ~1 month
  • Scan Lightning invoices
  • Top-up via Lightning invoice generated by the main Cashu mint

Running the project

Requirements: Node.js + npm.

npm install
npm run dev

Production build:

npm run build

Preview production build:

npm run preview