UUID Generator — v4 and v7, in Bulk, With a Decoder
Generate random v4 UUIDs or time-ordered v7 UUIDs, from one up to 10,000 at a time. Format them in upper case, without hyphens or in braces, and copy or download them as a plain list, a JSON array, SQL values or CSV. Paste any UUID to see its version, variant and — for time-based versions — when it was made. Everything is generated on your device with the Web Crypto API.
What UUID Generator does
Time-ordered v7, properly sorted
Version 7 puts a millisecond timestamp first, so new IDs append to the end of a database index instead of landing at random. A 12-bit counter keeps a bulk batch in exact creation order even inside one millisecond — many generators only get this right by luck.
Bulk, in the format you paste into
Up to 10,000 IDs at once, as one per line, a JSON array for fixtures, quoted SQL values for an INSERT, or a comma-separated list.
Decode any UUID
Paste a UUID from a log or a database and see its version, its variant and, for v1, v6 and v7, the exact moment it was created. It also tells you when a string is not a valid UUID at all.
Secure randomness
IDs come from your browser's Web Crypto generator, the same source used for encryption keys — never from Math.random(), which is predictable.
Formats for every system
Lower or UPPER case, with or without hyphens, and {braces} for the GUID style used in Windows, .NET and the registry. Changing a format keeps the same IDs.
Nothing is sent anywhere
Generation and decoding both run in your browser, so there is no server that ever sees or logs the IDs you create.
Supported formats
The formats and standards this tool works with.
How it works
Pick a version
v4 for random IDs, v7 for IDs that sort by creation time.
Choose how many
One, or up to 10,000. Press New for a fresh set.
Format and copy
Set case, hyphens and braces, pick a list style, then copy or download.
Decode (optional)
Paste any UUID in the decoder to see what kind it is and when it was made.
Cheatsheet
The tokens you reach for most, at a glance.
xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxxv4: the 4 marks the version, y is 8, 9, a or btttttttt-tttt-7xxx-yxxx-xxxxxxxxxxxxv7: first 48 bits (t) are Unix milliseconds00000000-0000-0000-0000-000000000000Nil UUID — often means "no value"ffffffff-ffff-ffff-ffff-ffffffffffffMax UUID — a sentinel for "largest"{…}Microsoft GUID styleurn:uuid:…URN form used in XML and some APIsHow people use it
Database primary keys
Use v7 for keys that stay fast to insert into a B-tree index at scale.
Test fixtures and seed data
Generate a JSON array or SQL value list of IDs to drop straight into a fixture or migration.
Debugging
Decode an ID from a log to see which service version made it and when.
Idempotency keys and correlation IDs
Grab a random v4 to tag a request, a job or an API call.
Frequently asked questions
Should I use UUID v4 or v7?
Use v7 for primary keys in your own database: it sorts by time, so inserts append to the index. Use v4 where an ID is public and its creation time should stay private, because anyone can read the timestamp out of a v7. The trade-offs are covered in UUID v4 vs v7.
Are these UUIDs really unique?
For all practical purposes. A v4 has 122 random bits: you would need about 2.7 quintillion of them for a 50% chance of a single repeat. A v7 has 74 random bits, but they only need to differ within the same millisecond.
Is a GUID the same as a UUID?
Yes. GUID is Microsoft's name for the same 128-bit identifier. Windows tools often write it in upper case inside braces — tick UPPER CASE and Braces to match.
Can I get the date out of a UUID?
For versions 1, 6 and 7, yes — paste it into the decoder. Version 4 is pure randomness, so it holds no date.
Why do my v7 UUIDs from the same batch all start the same?
The first 12 hex digits are the timestamp in milliseconds, and a batch is made within a few milliseconds. The digits after it are a counter and random bits, which is what keeps each one unique and in order.
Is it safe to use a generated UUID as a secret?
A v4 from this tool is cryptographically random, but a UUID is an identifier, not a password. For tokens or keys, use the password generator — and never use a v7 as a secret, since part of it is a timestamp.
Last updated 2026-09-15