Are UUIDs suitable as primary keys?

Yes. Prefer v7 (or ULID) over v4 for large tables: random v4 keys scatter inserts across the index, while v7 keys are time-ordered. This tool generates both.

Can I generate the same UUID twice?

For v4, practically no: you would need to generate about 2.7 billion per second for 85 years to reach a 50% chance of one collision. v3/v5 are deliberately deterministic — the same namespace and name always give the same UUID.

Does v1 leak my MAC address?

Not here. The node field is 48 random bits with the multicast bit set, as RFC 9562 recommends, so nothing about your machine is embedded.

What is the difference between a UUID and a ULID?

Both are 128-bit ids. A ULID is 26 Crockford-base32 characters (48-bit timestamp + 80 random bits) and sorts lexicographically; a UUID v7 carries the same idea in the standard 8-4-4-4-12 hex layout that databases and libraries already understand.

UUID Generator & Inspector

Produce RFC 9562 UUIDs of every version: random v4, time-ordered v7 with a monotonic counter, v1/v6 timestamp UUIDs with a random node, and name-based v3/v5 from a namespace (DNS, URL, OID, X.500 or custom) and one name per line. ULIDs and nanoids are supported too. Output up to 500 at once as lines, a JSON array, CSV, a SQL INSERT or a quoted list, in canonical, hyphen-less, braces, URN, Base64 or byte-array form. The Inspect mode decodes version, variant, embedded timestamp, node and clock sequence; Validate checks a pasted list for validity and duplicates.

Runs locally in your browser

122 random bits. The default choice when you just need a unique id.

Generated (0)

Output will appear here…

Count

Kind

Format

standard

Output

0 chars

Count

Up to 500 at once. Enter or ⌘/Ctrl+Enter regenerates.

Format

Uppercase

Password Generator

Strong random passwords, diceware passphrases, PINs and pronounceable codes with crack-time estimates.

Random Number Generator

Random integers and decimals, normal/exponential/weighted distributions, dice rolls, coin flips, and list shuffles or raffle picks.

Hash Generator

MD5, SHA-1, SHA-256/384/512, SHA-3, CRC32 and xxHash32 for text, lines and files — with verify and checksum export.

How to use UUID Generator & Inspector

1Pick a version (v4 for random, v7 for sortable database keys, v5 for deterministic ids).
2Set the count and output style — lines, JSON, CSV, SQL INSERT or quoted list.
3Copy one line, copy all, or download; ⌘/Ctrl+Enter regenerates and Undo restores the previous batch.
4Switch to Inspect to decode a UUID or ULID, or Validate to check a whole list.

About UUID Generator & Inspector

UUID Generator & Inspector is part of FizzKit — a collection of focused developer and ad-tech tools. Because everything runs locally, it works offline once loaded and never exposes your data to a remote server.

Frequently asked questions

v4 when you just need a unique random id. v7 for database primary keys — it starts with a Unix-millisecond timestamp, so rows insert in order and B-tree indexes stay compact. v5 when the same input must always map to the same id (e.g. deriving an id from a URL).

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