react-native-date

The fastest date library for React Native. Native C++ performance with zero-config localization.

Beta: This library is in active development. APIs may change.

Is this library for you?

Perfect for:

• Apps that render many dates (calendars, timelines, feeds, chat apps)
• Apps targeting low-end devices where JS performance matters
• Apps requiring multiple locales without bundle size bloat
• Apps that need timezone conversions at scale

Maybe not needed: If your app only formats a few dates occasionally, date-fns or Day.js work fine. This library shines when performance and localization are critical.

Why react-native-date?

Zero-Config Localization

No locale plugins. No imports. No bundles. Reads locales directly from the OS.

Library	Locale Support
date-fns	Import each locale (~3KB each)
Day.js	Plugin + import each locale
Moment.js	Full bundle (~300KB)
react-native-date	Built-in. Zero config.

import { format, setLocale } from '@bernagl/react-native-date';

// Uses device language automatically
format(Date.now(), 'MMMM'); // "November" (or user's language)

// Or set explicitly - no imports needed
setLocale('ja');
format(Date.now(), 'MMMM'); // "11月"

All 150+ locales supported by iOS/Android work out of the box.

Native Performance

Built with C++ and Nitro Modules for synchronous, near-native speed.

iPhone 14 Pro (ops/sec - higher is better):

Operation	Native	date-fns	Day.js	Luxon	Gain
parse()	2.0M	94K	329K	28K	🟢 21x
format()	771K	31K	103K	34K	🟢 25x
diffInDays()	1.6M	74K	104K	8K	🟢 22x
formatUTC()	805K	18K	80K	29K	🟢 45x

Low-End Android (ops/sec - higher is better):

Operation	Native	date-fns	Day.js	Luxon	Gain
parse()	465K	13K	46K	4K	🟢 35x
format()	270K	5K	16K	5K	🟢 54x
diffInDays()	351K	13K	15K	1K	🟢 27x
formatUTC()	292K	2K	12K	4K	🟢 146x

Performance gap widens on budget devices: format() is 25x faster on iOS but 54x faster on low-end Android. The native C++ implementation shines where JavaScript is constrained. Essential for apps targeting emerging markets.

Benchmarks from the example app Benchmark tab (1,000 iterations). We're actively working on optimizing addMonths() to win all 16 benchmarks.

See full benchmarks for all operations.

Familiar API

Works like date-fns or Day.js:

// Functional (date-fns style)
import { format, addDays } from '@bernagl/react-native-date';
format(addDays(Date.now(), 7), 'yyyy-MM-dd');

// Chainable (Day.js style)
import { nativeDate } from '@bernagl/react-native-date';
nativeDate().addDays(7).format('yyyy-MM-dd');

Requirements

Platform	Minimum Version
iOS	13.0+
Android	API 24+ (Android 7.0)
React Native	0.76+ (New Architecture)

Installation

npm install @bernagl/react-native-date react-native-nitro-modules

cd ios && pod install

No additional setup required.

Quick Start

import {
  now,
  format,
  addDays,
  diffInDays,
  isToday,
  setLocale,
  getTimezone
} from '@bernagl/react-native-date';

// Current timestamp
const timestamp = now();

// Format (uses device locale automatically)
format(timestamp, 'EEEE, MMMM d, yyyy');

// Date math
const nextWeek = addDays(timestamp, 7);
diffInDays(nextWeek, timestamp); // 7

// Predicates
isToday(timestamp); // true

// Timezone
getTimezone(); // "America/New_York"

// Localization
setLocale('es');
format(timestamp, 'EEEE, d MMMM'); // "domingo, 30 noviembre"

Features

• Fast - C++ core, no bridge overhead
• Zero-config locales - Reads from OS
• 150+ locales - All iOS/Android locales
• Timezone support - Full IANA database
• Tiny footprint - No locale bundles
• Type-safe - Full TypeScript support
• Two API styles - Functional or chainable

How Locales Work

Uses native OS APIs - no JavaScript locale data:

Platform	Native Classes
iOS	NSLocale, NSDateFormatter
Android	java.util.Locale, DateFormatSymbols

If setLocale() is never called, the library uses the device's language automatically.

Documentation

Full documentation available at the docs site.

• API Reference
• Examples
• Locales

Contributing

See CONTRIBUTING.md for guidelines.

License

MIT © Luis Garcia