Rando

Rando is a library for generating identifiers. IDs are random and universally unique by default. Options can be modified to fit a wide variety of requirements. In a node environment, randomness is provided by the node:crypto module. In a browser environment, randomness is provided by the Web Crypto API.

Install

npm i @balancer-team/rando

Usage

Import the rando class and create an instance. The instance generates IDs with the generate() method.

import { Rando } from '@balancer-team/rando'

const rando = new Rando()
rando.generate() // => "Jb46bM8xM3mhDLnpQrwNvN"

Customizing the Length

If you want a longer random string, for example if you want extra security for an API key, it's easy to modify the length. The example below generates a 46-character ID with over 256 bits of entropy:

const rando = new Rando({ length: 46 })
rando.generate() //=> "X5533mwXPH6V2nMN5548t1vkFVN4RTJqM89JNQcbVjmt1G"

Sortable IDs

Rando can generate sortable IDs where the beginning of the ID is an encoded timestamp using the given alphabet. Rando will evaluate the alphabet length and automatically determine how many characters are required to encode a timestamp at millisecond precision. The length must be sufficient for millisecond precision. Refer to the table below for guidance on the length needed to support a given year with a given alphabet base.

const rando = new Rando({ sortable: true })
rando.generate()

// Output:
//
// "13DNYFr2DBJvhWfWCs58Nb"
//  |------||------------|
//  Sortable    Random
//  Segment     Segment

Sortable IDs can be decoded to return a date. Note that the instance doing the decoding must have the same options as the instance that generated it.

rando.getDate('13DNYFr2DBJvhWfWCs58Nb').toISOString() //=> "2025-02-25T13:11:45.061Z"

All Options

Rando instances can be extensively customized to generate the perfect identifier for your requirements. Here's the type definition of all available options, with details below:

type RandoOptions = {
  alphabet?: string
  length?: number
  sortable?: boolean
  supportDate?: Date
}

Property	Default	Description
alphabet	BASE_50	A string of characters to use to generate your IDs. Each character must be unique. The default base 50 alphabet excludes vowels and ambiguous characters.
length	22	The length of the ID. By default, the length is 22 which provides 124 bits of entropy, slightly more than a UUIDv4.
sortable	false	Makes the ID sortable when set to true. The leading characters encode a timestamp at millisecond precision.
supportDate	'4000'	Allows you to specify a target date for the sortable segment. See below for additional details.

Special Considerations for Sortable IDs

The length and base of the alphabet together determine how long the sortable segment must be for millisecond precision. If the length is too short, Rando will throw an error when instantiated. The supportDate property allows you to specify a target date for the sortable segment to support. The sortable segment will be left-padded to support the target date with a consistent overall length.

Note that making an ID sortable will reduce the number of random characters in the ID. If you console.log the instance, you will see several helpful properties such as randomBits that can help you determine whether or not the ID meets your requirements.

const rando = new Rando({ sortable: true })

// Output:
//
// Rando {
//   alphabet: '123456789BCDFGHJKLMNPQRSTVWXYZbcdfghjkmnpqrstvwxyz',
//   length: 22,
//   randomLength: 13,
//   base: 50,
//   randomBits: 73.37013046707142,
//   randomLimit: 1.2207031249999986e+22,
//   sortable: true,
//   supportDate: 4000-01-01T00:00:00.000Z,
//   sortableLength: 9,
//   sortableLimit: +063862-01-25T10:13:20.000Z
// }

Presets

Rando comes with a few presets to make it easy to generate IDs for common use cases.

import { rando, sorto, locker, sesame, pinto } from '@balancer-team/rando/presets'

rando.generate() //=> "7kFD8XHYp1JdXXzYsxRvXT"
sorto.generate() //=> "13DNYDsRBvc6TQ2HwHh1GW"
locker.generate() //=> "5Myvnv4BQm7rDhz3zntYGMXf9Srr71z7wFwF1SSYMQVvQQ"
sesame.generate() //=> "E@MvHJG4JbA$o{8ll0AK"
pinto.generate() //=> "368230"

• rando Default, like a compact UUIDv4.
• sorto Sortable string followed by a random string, like a compact UUIDv7.
• locker Long string with over 256 bits of entropy, suitable for API keys.
• sesame Secure password with over 128 bits of entropy.
• pinto Numerical 6-digit pin for verification codes.

Guidance for Sortable IDs

The following table is a guide for the length needed to support at least the year 3000 with a given alphabet base.

Base	Length	Max Year
2	46	4199
3	29	4144
4	23	4199
5	20	4992
6	18	5188
7	17	9341
8	16	10889
9	15	8494
10	14	5138
11	14	14003
12	13	5360
13	13	11567
14	13	27121
15	12	6081
16	12	10889
17	12	20432
18	11	4006
19	11	5661
20	11	8459
21	11	13069
22	11	20486
23	11	32163
24	11	50190
25	10	4992
26	10	6443
27	10	8494
28	10	11356
29	10	15301
30	10	20681
31	10	27942
32	10	37648
33	10	50503
34	10	67387
35	9	4467
36	9	5188
37	9	6088
38	9	7205
39	9	8584
40	9	10277
41	9	12344
42	9	14856
43	9	17896
44	9	21557
45	9	25948
46	9	31193
47	9	37433
48	9	44832
49	9	53572
50	9	63862
51	9	75936
52	9	90061
53	9	106535
54	8	4261
55	8	4623
56	8	5034
57	8	5501
58	8	6028
59	8	6622
60	8	7292
61	8	8044
62	8	8888
63	8	9833
64	8	10889