How to generate UUIDs
- Pick the ID type: UUID v4, UUID v7, ULID, Nano ID or the nil UUID.
- Enter how many you need, from 1 to 10,000, and choose formatting: uppercase, no hyphens, braces (as used by Microsoft GUIDs) or quoted with commas for pasting into code or SQL.
- Press Generate, then copy the list or download it as a text file.
- Paste any existing ID into Inspect to check it is valid and see its version, variant and, for v1, v7 and ULID, the time it was created.
Which ID should I use?
UUID v4 is 122 bits of randomness and is the default choice for most applications. UUID v7 (standardised in RFC 9562 in 2024) starts with a millisecond timestamp, so new IDs sort after older ones. That keeps database B-tree indexes compact and inserts fast, which is why v7 is now recommended for primary keys. ULID has the same time-ordered idea in a shorter 26-character Base32 form that is easy to read and copy. Nano ID is a compact URL-friendly random ID with a configurable length, popular for short links and front-end keys.
All randomness comes from crypto.getRandomValues, the browser's cryptographically secure generator, so the IDs are safe to use as unguessable identifiers. Generated v7 IDs within the same millisecond use a counter so they stay strictly ordered.
Privacy
IDs are generated on your device. Nothing is sent to or logged on a server, so no one else ever sees the values you create.
Is a GUID the same as a UUID?
Yes. GUID is Microsoft's name for the same 128-bit identifier. Windows tools often show GUIDs in uppercase with braces, which you can switch on above.
Can two UUID v4 values collide?
In practice, no. You would need to generate about a billion UUIDs per second for around 85 years to reach a 50% chance of a single duplicate.
Does a UUID v7 reveal when it was created?
Yes, the first 48 bits are a Unix timestamp in milliseconds. If creation time is sensitive, use v4 instead.