react-native-ulid-jsi

⚡️ Ultra-fast ULID (Universally Unique Lexicographically Sortable Identifier) generator for React Native

Built with JSI (JavaScript Interface) and C++ for maximum performance. Features monotonic generation with thread-local state for guaranteed ID ordering. Supports both New Architecture (Fabric + TurboModules) and Old Architecture on iOS and Android.

🚀 500x faster than JavaScript | 🔄 Monotonic | 📦 Zero dependencies

🚀 Performance

500x faster than pure JavaScript implementations!

Comparison performed against the official ulid/javascript package.

Implementation	Time (1000 iterations)	Performance
react-native-ulid-jsi (JSI/C++)	0.17ms	⚡️ 500x faster
Pure JavaScript (ulid package)	83.62ms	🐌 Baseline

react-native-ulid-jsi  ▓ 0.17ms
JavaScript ULID        ▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓▓ 83.62ms
                       └────────────────────────────────────────────────┘
                                    500x performance gain

Benchmark performed on iPhone 16 Pro with production build

Why so fast?

1. Zero Bridge Overhead: Direct JSI binding to C++ (no serialization)
2. Native Random Generation: Platform-specific secure random APIs
3. Optimized Encoding: Hand-tuned Base32 encoding in C++
4. Thread-local State: No synchronization overhead for monotonic generation
5. Minimal Allocations: Stack-allocated buffers, no heap fragmentation

Run your own benchmark

import { ulid } from 'react-native-ulid-jsi';

const iterations = 1000;
const start = performance.now();

for (let i = 0; i < iterations; i++) {
  ulid();
}

const end = performance.now();
console.log(`Generated ${iterations} ULIDs in ${(end - start).toFixed(2)}ms`);
// Output: Generated 1000 ULIDs in 0.17ms

✨ Features

• ⚡️ Lightning Fast - JSI + C++ implementation for native performance
• 🏗️ New Architecture Ready - Full support for React Native's new architecture (Fabric + TurboModules)
• 🔄 Backward Compatible - Works seamlessly with old architecture
• 📱 Cross Platform - iOS and Android support
• 🎯 Type Safe - Full TypeScript support
• 🪶 Lightweight - Zero dependencies, pure C++ implementation
• 📈 Monotonic Generation - Guarantees increasing IDs even within the same millisecond
• ⏱️ Timestamp Encoded - Contains creation timestamp (first 48 bits)
• 🎲 Cryptographically Secure - Platform-native secure random generation
  • iOS: SecRandomCopyBytes (Security Framework)
  • Android: getrandom when available, falls back to /dev/urandom
• 🔤 Crockford's Base32 - Excludes ambiguous characters (I, L, O, U)

📦 Installation

npm install react-native-ulid-jsi

or with yarn:

yarn add react-native-ulid-jsi

iOS

cd ios && pod install

Android

No additional steps required. Gradle will handle everything automatically.

📖 Usage

Basic Usage

import { ulid } from 'react-native-ulid-jsi';

// Generate a new ULID
const id = ulid();
console.log(id); // 01ARZ3NDEKTSV4RRFFQ69G5FAV

// Generate multiple ULIDs - they will be monotonically increasing
const id1 = ulid(); // 01HGW4Z6C8ABCDEFGHIJKLMNOP
const id2 = ulid(); // 01HGW4Z6C8ABCDEFGHIJKLMNPQ (guaranteed > id1)
const id3 = ulid(); // 01HGW4Z6C8ABCDEFGHIJKLMNPR (guaranteed > id2)

With Seed Time

import { ulid } from 'react-native-ulid-jsi';

// Generate ULID with custom timestamp (milliseconds since epoch)
const timestamp = Date.now();
const id = ulid(timestamp);
console.log(id); // 01ARZ3NDEKTSV4RRFFQ69G5FAV

Validate ULID

import { isValid } from 'react-native-ulid-jsi';

const id = '01ARZ3NDEKTSV4RRFFQ69G5FAV';
const valid = isValid(id);
console.log(valid); // true

Decode Timestamp

import { decodeTime } from 'react-native-ulid-jsi';

const id = '01ARZ3NDEKTSV4RRFFQ69G5FAV';
const timestamp = decodeTime(id);
console.log(timestamp); // 1469918176385
console.log(new Date(timestamp)); // 2016-07-31T04:42:56.385Z

🎯 API Reference

ulid(seedTime?: number): string

Generates a new ULID.

Parameters:

• seedTime (optional): Custom timestamp in milliseconds since Unix epoch. If not provided, uses current time.

Returns: A 26-character ULID string.

Example:

const id1 = ulid(); // Uses current time
const id2 = ulid(1469918176385); // Uses custom time

isValid(id: string): boolean

Validates whether a string is a valid ULID.

Parameters:

• id: String to validate

Returns: true if valid ULID, false otherwise.

Example:

isValid('01ARZ3NDEKTSV4RRFFQ69G5FAV'); // true
isValid('invalid-id'); // false

decodeTime(id: string): number

Extracts the timestamp from a ULID.

Parameters:

• id: Valid ULID string

Returns: Timestamp in milliseconds since Unix epoch.

Example:

const timestamp = decodeTime('01ARZ3NDEKTSV4RRFFQ69G5FAV');
console.log(new Date(timestamp)); // Original creation time

🏗️ Architecture Support

This library is built to support both React Native architectures:

New Architecture (Fabric + TurboModules)

✅ Fully supported with JSI direct bindings ✅ Zero overhead JavaScript ↔️ Native communication ✅ Synchronous API access

Old Architecture (Bridge)

✅ Fully supported with JSI module installation ✅ Same performance benefits ✅ No breaking changes required

The library automatically detects and works with the architecture your app is using.

🔍 What is ULID?

ULID (Universally Unique Lexicographically Sortable Identifier) is a better alternative to UUID for many use cases:

• Sortable: Unlike UUIDs, ULIDs are lexicographically sortable
• Timestamp: Contains a timestamp component (first 48 bits)
• Compact: 26 characters vs UUID's 36 characters
• URL-safe: Uses Crockford's base32 encoding
• Case-insensitive: Easy to use in various contexts
• No special characters: Just alphanumeric characters

ULID Format

 01AN4Z07BY      79KA1307SR9X4MV3
|----------|    |----------------|
 Timestamp       Randomness
  (48 bits)       (80 bits)

🔄 Monotonic Generation

This library implements monotonic ULID generation, ensuring that IDs are always increasing even when generated within the same millisecond.

How it works:

1. Same timestamp: If multiple ULIDs are generated in the same millisecond, the random component is incremented instead of generating new random bytes
2. Overflow protection: If the random component overflows, a new random value is generated
3. Time progression: When time advances, a fresh random value is used

Why monotonic?

// Without monotonic (pure random):
const id1 = ulid(); // 01HGW4Z6C8ABCDEFGHIJKLMNOP
const id2 = ulid(); // 01HGW4Z6C8ZYXWVUTSRQPONMLK  ❌ Not guaranteed to be > id1

// With monotonic (this library):
const id1 = ulid(); // 01HGW4Z6C8ABCDEFGHIJKLMNOP
const id2 = ulid(); // 01HGW4Z6C8ABCDEFGHIJKLMNPQ  ✅ Always > id1

Benefits:

• ✅ Database indexes work optimally (B-tree friendly)
• ✅ No collisions within same millisecond
• ✅ Guaranteed sortability
• ✅ Better for distributed systems

💡 Use Cases

• Database IDs: Sortable by creation time without separate timestamp field
• Distributed Systems: Generate unique IDs without coordination
• API Resources: URL-safe identifiers for REST APIs
• Event Sourcing: Time-ordered events with unique identifiers
• Logging: Sortable log entry identifiers
• File Names: Unique, sortable file names

🔧 Technical Details

• Implementation: Pure C++ with JSI (JavaScript Interface) bindings
• Monotonic Generation: Thread-local state ensures IDs increment even within same millisecond
• Thread Safety: Thread-local storage per thread, no locks or mutexes needed
• Random Generation (with automatic fallback):
  • iOS: SecRandomCopyBytes (Security Framework)
  • Android: getrandom when available, falls back to /dev/urandom
  • Last resort: std::random_device (other platforms)
• Encoding: Crockford's Base32 (0-9, A-Z excluding I, L, O, U)
• Memory: Minimal allocation, optimized for mobile devices
• Dependencies: Zero - pure C++ standard library
• Bundle Size: Native module only, zero JavaScript bundle impact
• Platforms: iOS 12+, Android API 21+

📊 Comparison with JavaScript ULID

Feature	react-native-ulid-jsi	JavaScript ULID
Performance	⚡️ 0.17ms (1000 ops)	🐌 83.62ms (1000 ops)
Speed Improvement	500x faster	Baseline
Implementation	C++ / JSI	JavaScript
Monotonic	✅ Thread-local	⚠️ Varies by package
Architecture Support	New + Old	N/A
Secure Random	✅ Platform native	⚠️ JS Math.random or crypto
Bundle Impact	Native only (0 KB JS)	+5-10 KB bundle
Dependencies	Zero	Varies

🤝 Contributing

Contributions are welcome! Please read our contributing guidelines and code of conduct.

Development Workflow

1. Fork the repository
2. Create your feature branch (git checkout -b feature/amazing-feature)
3. Commit your changes (git commit -m 'feat: add amazing feature')
4. Push to the branch (git push origin feature/amazing-feature)
5. Open a Pull Request

See CONTRIBUTING.md for detailed development setup.

📄 License

MIT © Alex Shumihin

🔗 Links

• GitHub Repository
• npm Package
• Issues
• ULID Specification

⭐️ Show Your Support

If this project helped you, please give it a ⭐️!

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Made with ❤️ using create-react-native-library