uniku

One library. Every ID format. Every runtime. Zero dependencies.

uniku /uˈniːku/ — Maltese for "unique"

import { uuidv7 } from 'uniku/uuid/v7'

const id = uuidv7()
// => "018e5e5c-7c8a-7000-8000-000000000000"

// Time-ordered: IDs sort by creation time
const [first, second, third] = [uuidv7(), uuidv7(), uuidv7()]
console.log(first < second && second < third) // true

At a Glance

| | uniku | uuid | nanoid | ulid | cuid2 | ksuid | |--------------------|:-----:|:----:|:------:|:----:|:-----:|:-----:| | UUID v4 | ✅ | ✅ | ❌ | ❌ | ❌ | ❌ | | UUID v7 | ✅ | ✅ | ❌ | ❌ | ❌ | ❌ | | ULID | ✅ | ❌ | ❌ | ✅ | ❌ | ❌ | | CUID2 | ✅ | ❌ | ❌ | ❌ | ✅ | ❌ | | Nanoid | ✅ | ❌ | ✅ | ❌ | ❌ | ❌ | | KSUID | ✅ | ❌ | ❌ | ❌ | ❌ | ✅ | | Tree-shakeable | ✅ | ❌ | ✅ | ✅ | ✅ | ✅ | | ESM-only | ✅ | ❌ | ✅ | ✅ | ✅ | ✅ | | Edge/Workers | ✅ | ⚠️ | ✅ | ⚠️ | ✅ | ✅ | | Byte ↔ String | ✅ | ✅ | - | ✅ | - | ✅ |

Note: Byte ↔ String conversion doesn't make sense for nanoid and cuid2, since they are string-native formats with no canonical binary representation.

Works Everywhere

Uses globalThis.crypto (Web Crypto API) — no Node.js-specific APIs.

Performance

| Generator | uniku vs npm | |-----------|-------------:| | ULID | 85× faster | | CUID2 | 8× faster | | KSUID | 1.5× faster | | UUID v7 | 1.1× faster | | Nanoid | ~comparable speed | | UUID v4 | npm is 1.1× faster |

Which ID Should I Use?

Quick Recommendations

| Use Case | Recommended | Why | |----------|-------------|-----| | Database primary keys | UUID v7 or ULID | Time-ordered for index efficiency | | URL shorteners | Nanoid | Compact, URL-safe characters | | Prevent enumeration | CUID2 | Non-sequential, secure | | Maximum compatibility | UUID v4 | Universal standard | | Distributed systems (high entropy) | KSUID | 128-bit payload, second precision |

Detailed Guide

UUID v4 — Use when you need maximum compatibility with existing systems.

• 36 characters, 122-bit entropy
• Universally supported by databases (native UUID type)
• Not time-ordered (random distribution)
• Best for: Legacy systems, cross-platform compatibility

UUID v7 — Use for database primary keys when you need RFC compliance.

• 36 characters, time-ordered with millisecond precision
• Native database support as UUID type
• Strictly monotonic within same millisecond
• Best for: PostgreSQL/MySQL primary keys, API identifiers

ULID — Use for database primary keys when you want URL-safe IDs.

• 26 characters, time-ordered with millisecond precision
• URL-safe (no hyphens), case-insensitive
• 80-bit random entropy per millisecond
• Best for: APIs, URLs, distributed systems needing sortability

KSUID — Use when you need highest collision resistance.

• 27 characters, time-ordered with second precision
• URL-safe, 128-bit random entropy (highest of all formats)
• Best for: Very high-volume distributed systems, event sourcing

Nanoid — Use for short, URL-friendly identifiers.

• 21 characters (configurable), 126-bit entropy
• Customizable alphabet and length
• Not time-ordered
• Best for: URL shorteners, session tokens, invite codes

CUID2 — Use when ID unpredictability matters.

• 24 characters (configurable), hash-based
• Non-sequential, prevents enumeration attacks
• Not time-ordered
• Best for: User-facing IDs where security matters

Binary Serialization: When to Use toBytes()

Formats with binary representations (UUID, ULID, KSUID) support toBytes() and fromBytes() for efficient storage:

// Store as BINARY(16) instead of VARCHAR(36)
const bytes = uuidv7.toBytes(id)  // 16 bytes
db.insert({ id: bytes })

// Retrieve and convert back
const id = uuidv7.fromBytes(row.id)

Benefits of binary storage:

• Up to 50% smaller: E.g., 16 bytes vs 36 characters for UUID
• Faster indexing: Binary comparison is faster than string comparison
• Reduced I/O: Less data transferred between app and database

When to use binary:

• High-volume tables (millions of rows)
• Performance-critical queries on ID columns
• Storage cost is a concern

When to keep strings:

• Debugging/logging convenience
• API responses (humans read them)
• Small tables where savings are negligible

| Format | String Length | Binary Size | Savings | |--------|--------------|-------------|---------| | UUID v4/v7 | 36 chars | 16 bytes | 56% | | ULID | 26 chars | 16 bytes | 38% | | KSUID | 27 chars | 20 bytes | 26% | | Nanoid | 21 chars | N/A | - | | CUID2 | 24 chars | N/A | - |

Note: Nanoid and CUID2 don't have binary representations because they're string-native formats with no canonical byte encoding.

Installation

# pnpm (recommended)
pnpm add uniku

# bun
bun add uniku

# npm
npm install uniku

# yarn
yarn add uniku

# deno
deno install npm:uniku

Bundle Impact

| Import | Minified + gzipped | |--------|-------------------:| | uniku/uuid/v4 | ~940 B | | uniku/uuid/v7 | ~1.1 KB | | uniku/ulid | ~1.5 KB | | uniku/cuid2 | ~1.1 KB* | | uniku/nanoid | ~938 B | | uniku/ksuid | ~1.0 KB |

Quick Start

UUID v4 (random)

import { uuidv4 } from 'uniku/uuid/v4'

const id = uuidv4()
// => "550e8400-e29b-41d4-a716-446655440000"

// Convert to/from bytes
const bytes = uuidv4.toBytes(id)
const str = uuidv4.fromBytes(bytes)

UUID v7 (time-ordered)

import { uuidv7 } from 'uniku/uuid/v7'

const id = uuidv7()
// => "018e5e5c-7c8a-7000-8000-000000000000"

// IDs are lexicographically sortable by creation time
const ids = [uuidv7(), uuidv7(), uuidv7()]
ids.sort() // Already in creation order

ULID (time-ordered)

import { ulid } from 'uniku/ulid'

const id = ulid()
// => "01HW9T2W9W9YJ3JZ1H4P4M2T8Q"

// Convert to/from bytes
const bytes = ulid.toBytes(id)
const str = ulid.fromBytes(bytes)

CUID2 (secure, non-time-ordered)

import { cuid2 } from 'uniku/cuid2'

const id = cuid2()
// => "pfh0haxfpzowht3oi213cqos"

// Custom length
const shortId = cuid2({ length: 10 })
// => "tz4a98xxat"

// Validation (type guard)
if (cuid2.isValid(maybeId)) {
  console.log(maybeId) // TypeScript knows this is a string
}

Nanoid (URL-friendly, custom alphabet)

import { nanoid } from 'uniku/nanoid'

const id = nanoid()
// => "V1StGXR8_Z5jdHi6B-myT"

// Custom size
const shortId = nanoid(10)
// => "IRFa-VaY2b"

// Custom alphabet and size via options
const hexId = nanoid({ alphabet: '0123456789abcdef', size: 12 })
// => "4f90d13a42bc"

KSUID (time-ordered, high entropy)

import { ksuid } from 'uniku/ksuid'

const id = ksuid()
// => "2QnJjKLvpSfpZqGiPPxVwWLMy2p"

// Convert to/from bytes
const bytes = ksuid.toBytes(id)
const str = ksuid.fromBytes(bytes)

// Extract timestamp (milliseconds)
const ts = ksuid.timestamp(id)

Migrating to uniku

From uuid

- import { v4 as uuidv4 } from 'uuid'
+ import { uuidv4 } from 'uniku/uuid/v4'

From nanoid

- import { nanoid } from 'nanoid'
+ import { nanoid } from 'uniku/nanoid'

From ulid

- import { ulid } from 'ulid'
+ import { ulid } from 'uniku/ulid'

From @paralleldrive/cuid2

- import { createId } from '@paralleldrive/cuid2'
+ import { cuid2 } from 'uniku/cuid2'

From @owpz/ksuid

- import { KSUID } from '@owpz/ksuid'
+ import { ksuid } from 'uniku/ksuid'

- const id = KSUID.random().toString()
+ const id = ksuid()

- const parsed = KSUID.parse(str)
- const timestamp = parsed.timestamp
+ const timestamp = ksuid.timestamp(str)

API Reference

uuidv4 (from uniku/uuid/v4)

uuidv4(options?: UuidV4Options): string
uuidv4(options: UuidV4Options | undefined, buf: Uint8Array, offset?: number): Uint8Array
uuidv4.toBytes(id: string): Uint8Array
uuidv4.fromBytes(bytes: Uint8Array): string
uuidv4.isValid(id: unknown): id is string
uuidv4.NIL  // "00000000-0000-0000-0000-000000000000"
uuidv4.MAX  // "ffffffff-ffff-ffff-ffff-ffffffffffff"

uuidv7 (from uniku/uuid/v7)

uuidv7(options?: UuidV7Options): string
uuidv7(options: UuidV7Options | undefined, buf: Uint8Array, offset?: number): Uint8Array
uuidv7.toBytes(id: string): Uint8Array
uuidv7.fromBytes(bytes: Uint8Array): string
uuidv7.timestamp(id: string): number
uuidv7.isValid(id: unknown): id is string
uuidv7.NIL  // "00000000-0000-0000-0000-000000000000"
uuidv7.MAX  // "ffffffff-ffff-ffff-ffff-ffffffffffff"

ulid (from uniku/ulid)

ulid(options?: UlidOptions): string
ulid(options: UlidOptions | undefined, buf: Uint8Array, offset?: number): Uint8Array
ulid.toBytes(id: string): Uint8Array
ulid.fromBytes(bytes: Uint8Array): string
ulid.timestamp(id: string): number
ulid.isValid(id: unknown): id is string
ulid.NIL  // "00000000000000000000000000"
ulid.MAX  // "7ZZZZZZZZZZZZZZZZZZZZZZZZZ"

cuid2 (from uniku/cuid2)

cuid2(options?: Cuid2Options): string
cuid2.isValid(id: unknown): id is string

nanoid (from uniku/nanoid)

nanoid(): string
nanoid(size: number): string
nanoid(options: NanoidOptions): string
nanoid.isValid(id: unknown): id is string

// Constant
URL_ALPHABET  // "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-"

ksuid (from uniku/ksuid)

ksuid(options?: KsuidOptions): string
ksuid(options: KsuidOptions | undefined, buf: Uint8Array, offset?: number): Uint8Array
ksuid.toBytes(id: string): Uint8Array
ksuid.fromBytes(bytes: Uint8Array): string
ksuid.timestamp(id: string): number
ksuid.isValid(id: unknown): id is string
ksuid.NIL  // "000000000000000000000000000"
ksuid.MAX  // "aWgEPTl1tmebfsQzFP4bxwgy80V"

Documentation

For advanced usage, examples, and contributing guidelines, see the full documentation on GitHub.

Related Projects

Third-party libraries that inspired this project:

• uuid: the most popular UUID library for JavaScript
• ulid: the reference ULID implementation for JavaScript
• @paralleldrive/cuid2: secure, collision-resistant IDs
• @owpz/ksuid: K-Sortable Unique Identifier
• nanoid: tiny, URL-friendly unique string ID generator

Other:

• pnpm-monorepo-template: the template I used to create this library

Author

Hi, I'm Alberto Schiabel, aka @jkomyno. You can follow me on:

• Github: @jkomyno
• X: @jkomyno

License

MIT — see LICENSE