UUID v7 generator

The snippets below build RFC 9562 §5.7: 48-bit Unix milliseconds, version nibble 7, variant 10xx, then random bits. CPython 3.14+ uuid.uuid7 is the named stdlib API. Node has no uuid.uuid7; crypto.randomUUID() is v4 only. The Node snippet uses Date.now() and crypto.randomBytes — the same POSIX-ms clock and CSPRNG family this page runs through crypto.getRandomValues(). For how v7 compares to v4 and v5, see UUID Versions Explained: v4 vs v1, v5, v7 and v8 (Format & Length).

const { randomBytes } = require('crypto');

function uuidv7(ms, rand) {
  const bytes = Buffer.from(rand);
  bytes[0] = Number((ms >> 40n) & 0xffn);
  bytes[1] = Number((ms >> 32n) & 0xffn);
  bytes[2] = Number((ms >> 24n) & 0xffn);
  bytes[3] = Number((ms >> 16n) & 0xffn);
  bytes[4] = Number((ms >> 8n) & 0xffn);
  bytes[5] = Number(ms & 0xffn);
  bytes[6] = (bytes[6] & 0x0f) | 0x70;
  bytes[8] = (bytes[8] & 0x3f) | 0x80;
  const hex = bytes.toString('hex');
  return hex.slice(0, 8) + '-' + hex.slice(8, 12) + '-' + hex.slice(12, 16) + '-' + hex.slice(16, 20) + '-' + hex.slice(20);
}

uuidv7(1700000000000n, Buffer.alloc(16))
// "018bcfe5-6800-7000-8000-000000000000"

uuidv7(BigInt(Date.now()), randomBytes(16))
// version 7, variant 8/9/a/b; bits 0–47 are Date.now()

import datetime as dt
import uuid

u = uuid.uuid7()
u.version
# 7
u.time  # 48-bit Unix ms; changes each call
dt.datetime.fromtimestamp(u.time / 1000, tz=dt.timezone.utc)
# datetime.datetime(..., tzinfo=datetime.timezone.utc)

This page does not implement RFC 9562 §6.2 Method 1, 2, or 3, so two IDs from the same millisecond are not ordered by click. CPython uuid.uuid7 does use Method 1. Both use the same POSIX-ms clock as Unix timestamp Milliseconds mode. 1700000000000 is 1700000000 seconds — 2023-11-14T22:13:20.000Z. The Node layout string uses zero rand_a / rand_b so the 48-bit field is visible; Generate never writes that all-zero tail. uuid.uuid7 takes no timestamp argument and will not print 018bcfe5-6800-7000-8000-000000000000. crypto.randomUUID() and uuid.uuid4 belong on the UUID v4 generator. uuid.uuid1 is Gregorian 100-ns time plus a node id, not Unix ms. uuid.uuid6 and uuid.uuid8 are also 3.14+ and are not offered here. The high bits leak the minting millisecond; this is not a password hasher. For seconds vs milliseconds, see Unix Seconds vs Milliseconds: UTC vs Local. Sibling time-ordered IDs are ULID generator.

Generate on this page writes lowercase RFC 9562 §5.7 UUIDs with hyphens — one ID per line. Bits 0–47 are Date.now() Unix milliseconds. There is no §6.2 monotonic counter. util-linux 2.41+ uuidgen --time-v7 calls uuid_generate_time_v7(): the same 48-bit Unix-ms field from gettimeofday, ten random bytes, then version nibble 7 and variant 10xx. That command also skips §6.2, so two IDs from the same millisecond are not ordered. CPython 3.14+ python -m uuid -u uuid7 calls uuid.uuid7() and prints the same lowercase hyphenated layout — with §6.2 Method 1, unlike this page and uuidgen --time-v7. Default python -m uuid is v4. 3.12 and 3.13 reject -u uuid7. These commands mint a new ID each run — they do not decode or validate a pasted UUID.

uuidgen --time-v7
# lowercase 8-4-4-4-12; version nibble is 7

uuidgen --time-v7 --count 3
# three independent v7 lines; no §6.2 counter

uuidgen
# uppercase 8-4-4-4-12; version nibble is 4

uuidgen --time-v7
# unrecognized option

# 3.14+: lowercase hyphenated v7 (same layout this page writes)
python -m uuid -u uuid7
# lowercase 8-4-4-4-12; version nibble is 7

# 3.14+: batch in one process (Method 1). This page clamps 1–100
# and does not order same-ms IDs; the CLI has no 100 cap.
python -m uuid -u uuid7 -C 3
# three v7 lines; same-ms IDs stay ordered

# 3.12 / 3.13 reject the version
python -m uuid -u uuid7
# invalid choice: 'uuid7'

Default uuidgen and uuidgen --random are UUID v4 — use the UUID v4 generator. uuidgen --time is v1. uuidgen --time-v6 is v6, not this page. --sha1 / --md5 with --namespace and --name are hash-based v5 / v3 — use the UUID v5 generator. /proc/sys/kernel/random/uuid is also v4. --count with --time-v7 loops uuid_generate_time_v7(); it is not the v1 clock cache. This page's Count (1–100) also mints independent v7s. CPython uuid.uuid7 and python -m uuid -u uuid7 do use §6.2 Method 1. python -m uuid -u uuid7 -C 3 loops that function in one process, so same-ms IDs in that batch stay ordered. Three separate python -m uuid -u uuid7 processes each start a new counter. Default python -m uuid and python -m uuid -C 3 are v4 — use the v4 generator. python -m uuid -u uuid1 is v1. python -m uuid -u uuid5 -n @dns -N www.example.com is v5. -u uuid6 and -u uuid8 are also 3.14+ and are not offered here. -u uuid3 is MD5 (v3) and is not offered here. print() adds a newline after every ID, including the last; this page joins with LF and does not. This page's Uppercase and Remove hyphens options are display-only; neither uuidgen nor python -m uuid has a hyphen-strip flag — use tr -d '-' for 32 hex digits. PowerShell [guid]::NewGuid().ToString() is lowercase hyphenated v4, not v7. Windows has no uuidgen --time-v7 unless WSL. Version details are in UUID Versions Explained: v4 vs v1, v5, v7 and v8 (Format & Length).