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UUID Generator

Generate v4, v7, NIL, and MAX UUIDs with hyphen, case, and brace formatting.

FormatRandom — 122 bits of entropy from getRandomValues.
Result5
1

c5732f32-ea66-434b-b399-33ff62fa7649

2

8a850be6-d0da-4641-a999-bb4cd2eb07a1

3

fbc9c2c4-36b2-4b5a-b8a3-cba174eb9a26

4

9feab3a3-1d42-46c9-9c42-30c751bf7c69

5

e25b4aeb-21a6-4e8b-b07f-1237ae2bf716

Inputs stay on this device. Every developer tool on TaskKit runs entirely in your browser. Tokens, payloads, and pasted text are not transmitted to TaskKit servers or third parties.

What this tool does

Generates UUIDs in the formats engineers actually use: v4 (random), v7 (timestamp-prefixed, sortable), and the special NIL and MAX values. Output is configurable — hyphenated or compact, lowercase or uppercase, with or without curly braces — so you can match whatever your target system expects. You can generate up to 1,000 at a time.

When you'd use it

  • Producing primary keys for a new table without a database round-trip.
  • Generating idempotency keys for retryable API calls.
  • Filling test fixtures with stable but unique IDs.
  • Migrating off auto-increment integer IDs to opaque identifiers.

How it works

v4 UUIDs come from crypto.getRandomValues, the browser's CSPRNG. The version (4) and variant (RFC 4122) bits are set per spec, leaving 122 bits of randomness — collision probability is effectively zero for any realistic generation rate.

v7 UUIDs encode a 48-bit Unix millisecond timestamp followed by 74 random bits. Because the timestamp leads, v7 IDs sort lexicographically by creation time, which makes them cache-friendlier than v4 in B-tree indexes. They were standardized in RFC 9562 (May 2024).

Notes

Should I switch from v4 to v7 for database keys? Probably yes for new tables. v7 IDs cluster by insertion time, which keeps recent rows on the same index pages and reduces write amplification. The downside is that creation time leaks into the ID — for opaque public IDs, stay on v4.

What's NIL vs MAX? NIL is all zeros (00000000-0000-0000-0000-000000000000) and MAX is all ones — sentinel values defined in RFC 9562 for "no UUID" and "the maximum UUID."

Are these cryptographically random? v4 yes. v7 has 74 random bits — also cryptographically derived, but timestamps reduce the search space for an attacker, so don't use v7 as a session token.

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