Project Name | Stars | Downloads | Repos Using This | Packages Using This | Most Recent Commit | Total Releases | Latest Release | Open Issues | License | Language |
---|---|---|---|---|---|---|---|---|---|---|
Spec | 7,694 | a month ago | 56 | gpl-3.0 | ||||||
The canonical spec for ulid | ||||||||||
Ulid | 3,702 | 1,063 | 1,766 | 19 days ago | 18 | June 22, 2022 | 3 | apache-2.0 | Go | |
Universally Unique Lexicographically Sortable Identifier (ULID) in Go | ||||||||||
Ulid | 507 | 13 | 10 | 7 months ago | 16 | September 15, 2020 | 5 | apache-2.0 | Python | |
Universally Unique Lexicographically Sortable Identifier (ULID) in Python 3 | ||||||||||
Uniuri | 394 | 236 | 231 | a year ago | 1 | October 07, 2022 | 1 | cc0-1.0 | Go | |
Go package uniuri generates random strings good for use in URIs to identify unique objects. | ||||||||||
Ulid | 377 | 13 | 1 | 6 months ago | 9 | March 01, 2021 | 1 | mit | Ruby | |
Universally Unique Lexicographically Sortable Identifier implementation for Ruby | ||||||||||
Nulid | 241 | 4 | 2 | 9 months ago | 11 | January 14, 2022 | 2 | mit | C# | |
.Net ULID implementation | ||||||||||
Python Ulid | 237 | 4 | 3 days ago | 7 | March 10, 2022 | 2 | mit | Python | ||
ULID implementation for Python | ||||||||||
Friendly Id | 182 | 1 | 1 | 5 months ago | 9 | April 04, 2019 | 1 | apache-2.0 | Java | |
Java Friendly Id for UUID | ||||||||||
Pgulid | 167 | 9 months ago | 4 | PLpgSQL | ||||||
Universally Unique Lexicographically Sortable Identifier (ULID) for PostgreSQL | ||||||||||
Uuidshortener | 68 | 3 | 10 years ago | 2 | March 24, 2015 | mit | Objective-C | |||
Convert UUID 32-character hex string into a Base32 short string and back. |
UUID can be suboptimal for many use-cases because:
Instead, herein is proposed ULID:
ulid() // 01ARZ3NDEKTSV4RRFFQ69G5FAV
From ourselves and the community!
Below is the current specification of ULID as implemented in ulid/javascript.
Note: the binary format has not been implemented in JavaScript as of yet.
01AN4Z07BY 79KA1307SR9X4MV3
|----------| |----------------|
Timestamp Randomness
48bits 80bits
Timestamp
Randomness
The left-most character must be sorted first, and the right-most character sorted last (lexical order). The default ASCII character set must be used. Within the same millisecond, sort order is not guaranteed
ttttttttttrrrrrrrrrrrrrrrr
where
t is Timestamp (10 characters)
r is Randomness (16 characters)
Crockford's Base32 is used as shown. This alphabet excludes the letters I, L, O, and U to avoid confusion and abuse.
0123456789ABCDEFGHJKMNPQRSTVWXYZ
When generating a ULID within the same millisecond, we can provide some
guarantees regarding sort order. Namely, if the same millisecond is detected, the random
component is incremented by 1 bit in the least significant bit position (with carrying). For example:
import { monotonicFactory } from 'ulid'
const ulid = monotonicFactory()
// Assume that these calls occur within the same millisecond
ulid() // 01BX5ZZKBKACTAV9WEVGEMMVRZ
ulid() // 01BX5ZZKBKACTAV9WEVGEMMVS0
If, in the extremely unlikely event that, you manage to generate more than 280 ULIDs within the same millisecond, or cause the random component to overflow with less, the generation will fail.
import { monotonicFactory } from 'ulid'
const ulid = monotonicFactory()
// Assume that these calls occur within the same millisecond
ulid() // 01BX5ZZKBKACTAV9WEVGEMMVRY
ulid() // 01BX5ZZKBKACTAV9WEVGEMMVRZ
ulid() // 01BX5ZZKBKACTAV9WEVGEMMVS0
ulid() // 01BX5ZZKBKACTAV9WEVGEMMVS1
...
ulid() // 01BX5ZZKBKZZZZZZZZZZZZZZZX
ulid() // 01BX5ZZKBKZZZZZZZZZZZZZZZY
ulid() // 01BX5ZZKBKZZZZZZZZZZZZZZZZ
ulid() // throw new Error()!
Technically, a 26-character Base32 encoded string can contain 130 bits of information, whereas a ULID must only contain 128 bits. Therefore, the largest valid ULID encoded in Base32 is 7ZZZZZZZZZZZZZZZZZZZZZZZZZ
, which corresponds to an epoch time of 281474976710655
or 2 ^ 48 - 1
.
Any attempt to decode or encode a ULID larger than this should be rejected by all implementations, to prevent overflow bugs.
The components are encoded as 16 octets. Each component is encoded with the Most Significant Byte first (network byte order).
0 1 2 3
0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1 2 3 4 5 6 7 8 9 0 1
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 32_bit_uint_time_high |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 16_bit_uint_time_low | 16_bit_uint_random |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 32_bit_uint_random |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
| 32_bit_uint_random |
+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+-+
Partly inspired by: