uniku


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

> uniku /uˈniːku/ — Maltese for "unique"

``ts
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.

$3










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?

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| 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 |

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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

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

`ts
// 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

`bash


pnpm (recommended)

pnpm add uniku

bun

bun add uniku

npm

npm install uniku

yarn

yarn add uniku

deno

deno install npm:uniku
`

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| 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

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`ts
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)
`

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`ts
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
`

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`ts
import { ulid } from 'uniku/ulid'

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

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

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`ts
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
}
`

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`ts
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"
`

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`ts
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

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

$3

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

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

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

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`diff
- 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

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`ts
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"
`

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`ts
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"
`

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`ts
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"
`

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

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

// Constant
URL_ALPHABET // "ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789_-"
`

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`ts
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