Nostr Development Kit (NDK)

NDK Mobile is a React Native/Expo implementation of the Nostr Development Kit designed for mobile platforms. Key features include:

• Multiple Signer Implementations: Supports NIP-07, NIP-46, and Private Key signing.
• Offline Support: Uses SQLite-based caching to enable offline capabilities.
• Subscription Management: Handles automatic reconnection for Nostr subscriptions.
• Mobile Integration: Built specifically for React Native and Expo compatibility.
• State Management: Provides React hooks for easy integration into mobile UI components.
• Wallet Support: Includes integrated wallet support.

@nostr-dev-kit/react provides React hooks and utilities designed to integrate Nostr functionality into React applications via NDK.

Key capabilities include:

• NDK Instance Management: Using useNDKInit and useNDK to manage the NDK lifecycle.
• User Management: Managing the current user with useNDKCurrentUser and resolving users from different formats with useUser.
• Profile Management: Accessing specific profile values via useProfileValue.
• Session & Subscriptions: Handling multi-user sessions and managing event subscriptions using modern callback patterns.

The @ndk/svelte registry is organized into several categories to help you find the right level of abstraction for your Nostr application:

• 🧱 Blocks: Complete, ready-to-use UI sections (e.g., login interfaces, thread viewers).
• 🛠️ Builders: Reusable stateful primitives for composing complex Nostr interactions.
• 🎨 Components: Individual UI elements for specific Nostr entities (e.g., users, articles, events, hashtags, media).
• 🎯 UI Primitives: Low-level, composable building blocks for custom layouts.
• 🛠️ Utilities: Helper functions for formatting, parsing, and data manipulation.
• 🎭 Icons: Optimized Svelte icon components.

NDK provides a comprehensive set of tools for Nostr development:

• Relay Management: Connection pool with automatic reconnection and failover.
• Subscription API: Flexible API with support for caching, batching, and auto-closing.
• Event Handling: Creation, validation, and wrappers for major NIPs (NIP-01, NIP-04, NIP-07, NIP-18, NIP-49, NIP-57, NIP-60, NIP-61).
• Signer Adapters: Support for private keys, encrypted keys (NIP-49), browser extensions (NIP-07), and remote signing (NIP-46).
• Caching: Pluggable cache adapters (Redis, Dexie, SQLite, etc.).
• NIP Support: Outbox model, Data Vending Machine (NIP-90), and Zap utilities (NIP-57, NIP-61).
• Framework Integration: Modular packages for Mobile, Svelte (4 and 5), and React.

NDK Mobile provides a specialized toolkit for building Nostr applications on mobile devices, including:

• Signer Support: Supports multiple implementations via NDK Core (NIP-07, NIP-46, Private Key) and NDK Mobile (NIP-55).
• Offline Support: Uses NDKCacheAdapterSqlite for SQLite-based caching.
• Subscription Management: Handles subscriptions with automatic reconnection logic.
• State Management: Provides React hooks via @nostr-dev-kit/react such as useNDKStore, useNDKSessions, and useSubscribe.
• Wallet Integration: Integrated support via @nostr-dev-kit/ndk-wallet.
• Persistent Sessions: Automatically saves and loads user sessions and signers using expo-secure-store.

NDK-Blossom provides a high-level interface for the Blossom protocol, supporting several Blossom Upgrade Documents (BUDs):

• File Upload: Automatic server selection.
• URL Healing: Finding alternative servers for broken URLs.
• Blob Management: List, retrieve, and delete blobs.
• Server Discovery: Using Kind 10063 user preferences.
• Mirroring: Copying blobs between servers (BUD-04).
• Media Optimization: Accessing resized or converted versions (BUD-05).
• Authentication: Using Nostr Kind 24242.
• Metadata: Support for Nostr File Metadata Tags (BUD-08).

The NDK Svelte Registry is a component library for Svelte 5 applications. It is organized into three hierarchical layers to support progressive enhancement:

1. UI Primitives (./ui/): Headless, unstyled building blocks. They use a composition pattern and are exported as namespaced objects (e.g., User.Root, User.Avatar). Use these when you need maximum flexibility or are building a custom design system.
2. Components (./components/): Pre-styled, opinionated implementations built on top of primitives using Tailwind CSS. They are exported as named components (e.g., UserCardPortrait). Use these for quick, standard layouts.
3. Blocks (./blocks/): Complete, production-ready feature implementations that combine multiple components and primitives (e.g., ThreadViewTwitter). Use these for complex, multi-component layouts like entire application sections.

NDK validation checks for several types of invalid data within subscription filters:

1. Undefined Values: Detects or removes undefined in any filter array.
2. Type Validation:
   • authors: Must be strings and valid 64-character hex pubkeys.
   • ids: Must be strings and valid 64-character hex event IDs.
   • kinds: Must be numbers (integers between 0-65535).
   • Tag filters (#e, #p, etc.): Must be strings. Specifically, #e and #p tags must be valid 64-character hex strings.
3. Invalid Data:
   • Non-string values in string arrays.
   • Non-numeric values in the kinds array.
   • Invalid hex strings where required.
   • Out-of-range kind numbers.

The ndk-wallet package provides a toolkit for managing various wallet types in the Nostr ecosystem. It is built around the NDKWallet interface, which serves as the base for all implementations, providing a common API for:

• Retrieving balances
• Sending and receiving payments
• Interacting with wallet events
• Managing wallet status

Key implementations include:

• NDKCashuWallet: NIP-60 Cashu eCash implementation.
• NDKNutzapMonitor: Automated monitoring and redemption of NIP-60 nutzaps.
• NDKWalletNWC: NIP-47 Nostr Wallet Connect client.