UUID Generator
Bulk-generate random RFC 4122 version 4 UUIDs.
UUIDs (universally unique identifiers) are used throughout software to label database rows, sessions, and objects with an identifier that's extremely unlikely to collide with any other. This tool generates one or many version-4 (random) UUIDs at once using the browser's native crypto.randomUUID function, then lets you copy them all in one go.
Why software needs identifiers that don't collide
In a system with multiple independent services or databases creating records at the same time, a simple auto-incrementing number (1, 2, 3...) doesn't work well, since two different services could both generate '1' for unrelated records with no way to tell them apart later, or to merge data from two systems without renumbering everything. A UUID sidesteps this entirely by being generated independently on each system while still being extremely unlikely to ever match another UUID generated anywhere else, without any central coordination needed.
What makes version 4 specifically 'random'
The UUID specification actually defines several different versions with different generation strategies — version 1 incorporates the generating computer's network address and a timestamp, version 5 is derived deterministically from a name using hashing, while version 4, the most commonly used today, is built almost entirely from random bits. Out of a UUID's 128 total bits, 122 are random in version 4, with the remaining bits fixed to specific values that identify it as a version-4 UUID according to the standard.
Just how unlikely is a UUID collision, really
With 122 random bits, the total number of possible version-4 UUIDs is roughly 2^122 — an almost incomprehensibly large number. To put the collision risk in perspective, you'd need to generate roughly a billion billion UUIDs before the probability of a single collision reaches even 50%, which is why UUIDs are trusted as unique identifiers across massive distributed systems without any central registry checking for duplicates.
How to use it
- Set how many UUIDs you want to generate.
- Click Generate.
- Review the list of UUIDs.
- Click Copy All to copy every UUID, one per line.
Common ways people use this tool
Seeding test data for a database
Generate a batch of unique IDs to populate test records without worrying about collisions with existing data.
Creating unique session or request identifiers
Generate a UUID to use as a unique tracking or session identifier during development or debugging.
Assigning IDs to new records in a script
Quickly generate the unique identifiers needed when writing a script that creates several new database entries at once.
Tips for getting the best results
- Generate UUIDs in the exact quantity you need for a batch task rather than generating one at a time repeatedly.
- Store the generated UUIDs immediately if you need them for a specific project — they aren't saved anywhere after you leave the page.
- Remember version-4 UUIDs carry no embedded information about when or where they were created, unlike some other UUID versions.
- Use the standard hyphenated format shown here directly — most systems and databases expect UUIDs in exactly this formatting.
Frequently asked questions
What does 'version 4' mean?
Version 4 UUIDs are generated from random or pseudo-random numbers, as opposed to versions based on timestamps or hardware identifiers — they're the most common type for general-purpose unique IDs.
How unlikely is a UUID collision?
With 122 random bits, the probability of two version-4 UUIDs colliding is astronomically small — practically negligible for real-world use.
Can I generate thousands at once?
Yes, though generating very large batches (tens of thousands) may take a moment since each one uses the browser's secure random number generator.
Are UUIDs the same thing as GUIDs?
Yes, GUID (Globally Unique Identifier) is essentially Microsoft's own terminology for the same underlying concept as a UUID; the formats are compatible.
Can a UUID be used as a database primary key?
Yes, it's a common practice, though UUIDs take up more storage space than simple auto-incrementing integers and can have different performance characteristics for database indexing.
Do UUIDs reveal any information about my device or location?
No — version-4 UUIDs are built almost entirely from random data and don't encode any identifiable information about the generating device.
Is there a visual pattern to a UUID's format?
Yes, it always follows an 8-4-4-4-12 hexadecimal character pattern separated by hyphens, with a fixed digit indicating the version in a specific position.
Can I generate a UUID without the hyphens, as one continuous string?
This version outputs the standard hyphenated format directly; if a system specifically requires no hyphens, they can be removed afterward with a quick find-and-replace.
Do UUIDs ever expire or need to be regenerated?
No, a UUID has no built-in expiry or time limit — once generated and assigned to a record, it remains valid and unique indefinitely.
Is it safe to use UUIDs in a public-facing URL?
Generally yes, since UUIDs don't reveal sequential information (unlike auto-incrementing IDs, which can hint at how many total records exist), making them a reasonable choice for identifiers exposed in public URLs.
Can two different applications generate the exact same UUID by coincidence?
Theoretically possible but so astronomically unlikely with 122 random bits that it's treated as effectively impossible in real-world system design, even across billions of independently generated UUIDs.
Is it fine to use UUIDs for something as simple as a to-do list app?
Yes, UUIDs work perfectly well even for small, low-stakes projects — their simplicity and collision-resistance make them a safe default choice regardless of project scale.