UUID Generator
Generate cryptographically secure UUIDs (GUIDs) instantly — random v4, sortable v7 for database keys, or classic v1. Create up to 10,000 at once and format them exactly the way your code needs.
What Is a UUID?
A 128-bit identifier you can create anywhere without asking a central server.
A UUID (Universally Unique Identifier) — called a GUID in the Microsoft world — is a 128-bit value written as 32 hex digits in five groups: 8-4-4-4-12, for example 3f2b8c1e-9d4a-4f6b-b2e1-7c5a0d9e8f13. The 13th digit tells you the version and the 17th the variant.
Because the space is so large (2122 random possibilities for v4), you can generate IDs independently on many machines, offline, and still not expect a collision in the lifetime of the universe.
Every UUID here is built from crypto.getRandomValues() — the browser's cryptographically secure random generator — never Math.random(). Nothing is sent to a server and nothing is logged.
UUIDs are identifiers, not secrets. They are fine for database keys and filenames, but if you need an unguessable token for password resets or sessions, use a dedicated random token with enough entropy and an expiry.
Which UUID Version Should You Use?
Versions defined in RFC 9562 (which replaced RFC 4122 in 2024).
Version 4 — random
122 random bits. The default choice for most apps, APIs and test data. Supported natively by crypto.randomUUID(), PostgreSQL gen_random_uuid() and every language.
Version 7 — time-ordered
A 48-bit Unix millisecond timestamp followed by random bits. IDs sort by creation time, which keeps B-tree indexes compact and inserts fast — the best choice for database primary keys.
Version 1 — timestamp + node
A 60-bit timestamp (100 ns since 1582) plus a node ID. Kept for legacy systems such as Cassandra timeuuid. This tool uses a random node ID instead of your MAC address, for privacy.
Nil UUID
All 128 bits set to zero: 00000000-0000-0000-0000-000000000000. Used as a placeholder or "no value".
How to Use the UUID Generator
Get your result in under ten seconds.
Pick a version
Choose v4 for general use, v7 for sortable database keys, v1 for legacy systems or Nil for a placeholder.
Set quantity and format
Generate 1 to 10,000 at once. Choose uppercase, no hyphens, quotes, braces or a JSON array — the list re-formats instantly.
Copy or download
Copy the list to your clipboard or download it as a .txt or .json file.
Why Use the UUID Generator on Developers Web Tools
Fast, accurate and private — built for developers.
Cryptographically secure
Built on crypto.getRandomValues(), the same secure source browsers use for encryption keys.
Sortable v7
RFC 9562 v7 with a monotonic counter, so IDs created in the same millisecond still sort in order.
Bulk generation
Create up to 10,000 UUIDs in milliseconds — ready for seed data, fixtures and migrations.
Format for any language
Quotes for code, braces for .NET GUIDs, urn:uuid: for XML, JSON arrays for APIs.
Decoded output
See the version, variant and embedded timestamp of the first generated UUID.
Private
Generated locally and never sent anywhere. Your v1 UUIDs don't reveal your MAC address.
Frequently Asked Questions
In theory yes, in practice no. With v4 you would need to generate about a billion UUIDs per second for 85 years to have a 50% chance of a single collision — provided a secure random source is used, as it is here.
Nothing meaningful — GUID (Globally Unique Identifier) is Microsoft's name for the same 128-bit format. .NET often displays GUIDs in uppercase with braces, which you can produce with the UPPERCASE and Braces options.
Prefer v7. Random v4 keys are inserted all over the index, causing page splits and poor cache use in large tables. v7 keys are time-ordered, so new rows append to the end of the index like an auto-increment ID, while staying globally unique.
A v7 UUID reveals when it was created, to the millisecond. That is usually harmless for database keys, but if creation time is sensitive, use v4 for public-facing IDs.
No. RFC 9562 says they should be generated in lowercase but compared case-insensitively. Uppercase is common in Microsoft tools; pick whichever your system expects.
No. They are generated in your browser with JavaScript and disappear when you close the page.