!@thi.ng/ksuid

!npm downloads

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> This is one of 214 standalone projects, maintained as part
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>
> 🚀 Please help me to work full-time on these projects by sponsoring me on
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- About
- CLI usage
- Status
- Breaking changes
- Related packages
- Installation
- Dependencies
- API
- Benchmarks
- Authors
- License

About

Configurable K-sortable unique IDs, ULIDs, binary & base-N encoded, 32/48/64bit time resolutions.

Idea based on segmentio/ksuid, though the
added flexibility in terms of configuration & implementation also enables the
creation of ULIDs:

| Feature | KSUID default | ULID default |
|---------------------------------------|----------------------------------|------------------------|
| Configurable bit size | 160 bits | 128 bits |
| Base-N encoding scheme | base62⁽¹⁾ | base32 (Crockford) |
| Timestamp resolution | seconds (32 bits) | milliseconds (48 bits) |
| | milliseconds (64 bits) | |
| Epoch start time offset | approx. 2020-09-13⁽²⁾ | none |
| Time-only base ID generation | ✅ | ✅ |
| ID parsing / decomposition | ✅ | ✅ |
| Configurable RNG source⁽³⁾ | ✅ | ✅ |

- ⁽¹⁾ See
@thi.ng/base-n
for alternatives
- ⁽²⁾ With the default offset, the max. supported date for KSUID32 is 2156-10-20T18:54:55Z
- ⁽³⁾ Default: window.crypto, Math.random as fallback

IDs generated w/ this package are composed of a 32, 48 or 64 bit Unix epochs and
N additional bits of a random payload (from a configurable source). By default
all timestamps are shifted to free up bits for the future. IDs can be generated
as byte arrays or base-N encoded strings. For the latter, the JS runtime MUST
support
BigInt.

!KSUID bit layout diagram

$3

Since v3.1.0 a small CLI for ad-hoc KSUID generation is included. Currently only
KSUID32 is supported and IDs are always based on the current time:

``bash
npx @thi.ng/ksuid


0dwncLZE8byaQdccncWDmsNmlYt

optionally provide number of random bytes to be used (default: 16)

npx @thi.ng/ksuid 8

01ogp9KDpWlQ0pXCY

`

Status

STABLE - used in production

Search or submit any issues for this package

$3

Since v3.0.0 all
epoch
time-shift config values are to be given in milliseconds. This change is
unifying this behavior and is only a breaking change if using KSUID32 and
specifying custom epoch offsets (using defaults is not impacted).
Previously, KSUID32 used an offset given in seconds, whereas the other
implementations already used milliseconds.

Related packages

- @thi.ng/base-n - Arbitrary base-n conversions w/ presets for base8/16/32/36/58/62/64/83/85, support for bigints and encoding/decoding of byte arrays
- @thi.ng/idgen - Generator of opaque numeric identifiers with optional support for ID versioning and efficient re-use
- @thi.ng/random - Pseudo-random number generators w/ unified API, distributions, weighted choices, ID generation

Installation

`bash
yarn add @thi.ng/ksuid
`

ESM import:

`ts
import * as ksuid from "@thi.ng/ksuid";
`

Browser ESM import:

`html

`

JSDelivr documentation

For Node.js REPL:

`js
const ksuid = await import("@thi.ng/ksuid");
`

Package sizes (brotli'd, pre-treeshake): ESM: 990 bytes

Dependencies

- @thi.ng/base-n
- @thi.ng/errors
- @thi.ng/random
- @thi.ng/strings

API

Generated API docs

`ts
import { defKSUID32, defKSUID64, defULID } from "@thi.ng/ksuid";

// init 32bit epoch (resolution: seconds) w/ defaults
const id = defKSUID32();
// init 64bit epoch (resolution: milliseconds), same API
const id = defKSUID64();
// init 48bit epoch (resolution: milliseconds), same API
const id = defULID();

id.next();
// '05XCWbXa3akRqLDBUw4ogCVKGkd'

const a = id.nextBinary()
// Uint8Array(20) [
// 0, 160, 48, 77, 101, 251,
// 244, 17, 155, 97, 24, 101,
// 70, 71, 207, 23, 32, 21,
// 244, 116
// ]

// format a binary KSUID
id.format(a);
// '05XCZ32AaDZfZt0SWE2C22o6cqK'

id.parse("05XCZ32AaDZfZt0SWE2C22o6cqK")
// {
// epoch: 1610498125000,
// id: Uint8Array(16) [
// 101, 251, 244, 17, 155, 97,
// 24, 101, 70, 71, 207, 23,
// 32, 21, 244, 116
// ]
// }

new Date(1610498125000).toISOString()
// '2021-01-13T00:35:25.000Z'
`

Creating custom IDs:

`ts
import { BASE36 } from "@thi.ng/base-n";

// using base36, no time shift, 64bit random part
const id36 = defKSUID32({ base: BASE36, epoch: 0, bytes: 8 });

id36.next();
// '2VOUKH4K59AG0RXR4XH'
`

Benchmarks

Benchmarks can be run via yarn bench. All timings in milliseconds (test
config: Node v20.4.0, MBA M1 2021, 16GB). The benchmark collects N KSUIDs w/
different configs in an array, with each case being run 100 times.

| Title| Iter| Size| Total| Mean| Median| Min| Max| Q1| Q3| SD%|
|------------------------|-------:|-------:|-----------:|-------:|-------:|-------:|-------:|-------:|-------:|-------:|
| b62, 128bit, n=10000| 100| 1| 2158.68| 21.59| 21.57| 19.91| 25.91| 20.42| 21.87| 6.26|
| b62, 64bit, n=10000| 100| 1| 1200.40| 12.00| 11.95| 11.27| 14.66| 11.82| 12.10| 3.99|

Authors

- Karsten Schmidt

If this project contributes to an academic publication, please cite it as:

`bibtex
@misc{thing-ksuid,
title = "@thi.ng/ksuid",
author = "Karsten Schmidt",
note = "https://thi.ng/ksuid",
year = 2020
}
``

License

© 2020 - 2026 Karsten Schmidt // Apache License 2.0