Why use UUIDv7 instead of UUIDv4 for database primary keys?

UUIDv7 embeds a 48-bit millisecond Unix timestamp at the beginning, making values naturally time-ordered and significantly reducing B-tree index fragmentation compared to random UUIDv4.

What is the difference between UUIDv1 and UUIDv6?

Both use Gregorian timestamps and node IDs, but UUIDv6 reorders the timestamp bits to place the most significant time components first, enabling chronological sorting.

Are UUIDv5 identifiers unique across repeated generations?

UUIDv5 is deterministic: passing the same namespace and string name will always produce the identical UUID output.

Which UUID versions support embedded timestamp extraction during decoding?

Decode mode extracts and displays human-readable UTC timestamps for time-based versions: v1, v6, and v7.

How many UUIDs can I generate in a single request?

You can generate anywhere from 1 to 100 UUIDs per run in either lowercase or uppercase formatting.

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UUID Version Generator (v1–v8)

Generate RFC 9562 UUIDs — including the modern v6, v7 and v8 that most generators lack — or decode any UUID back to its version, variant and embedded timestamp.

Details

What this tool helps you do

A full-range UUID generator covering every RFC 9562 version: v1 (time-based, Gregorian timestamp + node), v4 (random), v5 (deterministic SHA-1 namespaced with the DNS/URL/OID/X.500 namespaces), v6 (v1 with k-sortable reordered timestamp), v7 (48-bit Unix-millisecond timestamp + random — the database-friendly one that sorts correctly) and v8 (custom version field, filled with CSPRNG random here). Generate up to 100 at a time in lower- or uppercase. Switch to decode mode to parse any UUID: it reports the version, variant, and — for v1/v6/v7 — extracts the embedded timestamp and renders it as an exact UTC date, which is the quickest way to check whether a v7 is well-formed or where a v1 came from. The v5 mode is deterministic, so the same namespace + name always yields the same UUID.

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UUID Version Generator (v1–v8)

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Key facts

Overview

When to use

How it works

Use cases

Examples

1. Generate Database-Friendly UUIDv7 Batch

2. Decode an RFC 9562 Test Vector

FAQ

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