UUID Generator
Create one UUID or thousands — random version 4, database-friendly version 7, name-based version 5 or ULIDs — and decode any UUID to see its version and timestamp.
- v4 · v7 · v5 · ULID
- Up to 5,000
- UUID inspector
- Generated locally
Inspect a UUID
How to generate UUIDs
A fresh set is ready when the page opens.
- 1
Pick a version
Version 4 for general use, version 7 for database keys, version 5 when the same name must always give the same ID.
- 2
Set the amount and format
Choose how many, and whether you want plain lines, a JSON array, CSV or an SQL list.
- 3
Copy or download
Copy the list or save it as a file. Press Generate for a new set.
Every UUID version you actually need
Implemented according to RFC 9562.
Secure random source
Random bits come from the browser’s cryptographic generator (crypto.getRandomValues), not from Math.random.
Version 7 for databases
Time-ordered IDs keep B-tree indexes compact and inserts fast. Within one millisecond the IDs still increase.
Name-based versions 3 and 5
Turn names into repeatable UUIDs with the DNS, URL, OID or X.500 namespace — or your own.
ULID
26-character, URL-safe, sortable identifiers for when a shorter text form is welcome.
Ready-to-paste formats
JSON array, comma-separated, SQL IN list, with braces, quotes, URN prefix, uppercase or without hyphens.
Inspector
Paste any UUID to learn its version and variant, and the creation time hidden in v1, v6, v7 and ULID values.
Private by design
Everything runs in your browser. What you type or open is not sent to a server.
Free, no sign-up
No account, no limits, no watermark — on a phone, tablet or computer.
Which UUID version should you use?
A UUID (universally unique identifier, called GUID on Windows) is a 128-bit value written as 32 hexadecimal digits in five groups. It can be created anywhere without a central authority and still be unique for all practical purposes. Version 4 fills 122 bits with random data: you would need to generate about 2.7 quintillion of them before the chance of a single duplicate reaches 50 %.
Random UUIDs have one drawback as primary keys: new rows land at random positions of the index, which fragments it and slows down inserts on large tables. Version 7, standardized in RFC 9562 in 2024, solves this by starting with a millisecond timestamp, so new IDs are always appended at the end — while 74 random bits keep them unguessable. For new systems, v7 is the usual recommendation for database keys and v4 for everything else.
Versions 3 and 5 are not random at all: they hash a namespace and a name, so the same input always yields the same UUID — useful to derive stable IDs from URLs or e-mail addresses. Version 5 (SHA-1) is preferred over version 3 (MD5). Version 1 combines a timestamp with a node ID; classic implementations leaked the MAC address, which is why this tool always uses a random node.
UUID versions at a glance
| Version | Based on | Typical use |
|---|---|---|
| v4 | Random numbers | General-purpose IDs, tokens, file names |
| v7 | Unix time + random | Database primary keys, sortable event IDs |
| v5 / v3 | Namespace + name (SHA-1 / MD5) | Stable IDs derived from names or URLs |
| v1 / v6 | Timestamp + node | Legacy systems; v6 is the sortable form |
| ULID | Unix time + random, Base32 | Sortable IDs with a shorter text form |
Tips
- Need a fingerprint of content rather than a random ID? Use the Hash Generator.
- Decode the timestamp of a v7 UUID further with the Timestamp Converter.
- Print an ID on a label as a scannable code with the Barcode Generator or the QR Code Generator.
- Store UUIDs in a native UUID or BINARY(16) column rather than CHAR(36): it halves the size and speeds up comparisons.
Frequently asked questions
Can’t find your answer? Contact us — we reply quickly.
Are the generated UUIDs really unique?
Yes, for all practical purposes. A version 4 UUID contains 122 random bits from a cryptographically secure generator; a collision is so unlikely that it can be ignored.
What is the difference between UUID v4 and v7?
v4 is entirely random. v7 begins with the current time in milliseconds followed by random bits, so v7 values sort by creation time and behave much better as database keys.
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 uppercase and in braces — both formats are available here.
Can I generate the same UUID again?
Only with the name-based versions 3 and 5: the same namespace and name always produce the same UUID. Random and time-based versions differ every time.
Can someone read information from a UUID?
From v1, v6 and v7, yes: they contain their creation time, which the inspector shows. A v4 UUID carries no information. Do not use time-based IDs where the creation time must stay secret.
Is my data sent to a server?
No. The tool runs entirely in your browser. Your input is not uploaded, logged or stored on our servers.
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