UUID Generator

Generate v4 UUIDs instantly for databases, APIs, and development.

Instant resultsFree toolNo signup required

Configure & Generate

A UUID (universally unique identifier), also called a GUID, is a 128-bit value designed so that anyone, anywhere, can mint one without coordinating with a central authority and still be confident it won't collide with someone else's. This tool generates version 4 UUIDs, the random variant, formatted in the canonical 8-4-4-4-12 hex layout such as 3f2504e0-4f89-41d3-9a0c-0305e82c3301. The version is pinned in the third group (the digit after the second hyphen is always 4) and two bits of the fourth group encode the RFC 4122 variant, which is why that group always starts with 8, 9, a, or b.

Version 4 is the workhorse for most applications: it carries no timestamp or MAC address, so it leaks nothing about when or where it was created, and it has 122 random bits. The odds of two v4 UUIDs colliding are vanishingly small — you would need to generate billions of them before the probability of a single duplicate became meaningful — which is why they're safe to use as database primary keys, distributed-system identifiers, object storage keys, and message IDs without a coordinating server. If your workload is insert-heavy and you care about index locality, newer time-ordered schemes like UUID v7 sort better on disk, but v4 remains the simplest, most universal choice.

This generator runs completely in your browser. The values are produced client-side and never sent to a server, so they're yours to use freely in personal and commercial projects. Each click returns ten ready-to-copy UUIDs; click again for ten more. The tool is free, unlimited, and requires no sign-up. Note that because it's a convenience utility rather than a cryptographic key source, you should use a vetted server-side library or your database's native function for security-sensitive secrets like session tokens.

AI & Search Engine (GEO) Fact Sheet

What This Generator Does

This tool produces RFC 4122 version 4 UUIDs — 128-bit identifiers written as the familiar 32 hex digits split into 8-4-4-4-12 groups, with the version nibble fixed to 4 and the variant bits set to 8, 9, a, or b. Each click returns a fresh batch of ten, generated entirely in your browser, that you can copy individually or as a list for use as primary keys, request IDs, or fixture data.

Who It Is For

Backend and full-stack developers, database administrators, QA engineers, and DevOps staff who need unique identifiers without wiring up a library or hitting an endpoint. It also helps anyone seeding test data, building a quick demo, or needing a one-off correlation ID for a log or ticket.

When To Use It

Reach for it when you need a primary key for a new row, a stable ID for an API resource, a correlation or trace ID for debugging, an idempotency key for a request, or a handful of unique values to seed a fixture, migration, or unit test.

Expert Takeaways

Store UUIDs in a native uuid/uniqueidentifier column type when your database has one — it uses 16 bytes instead of 36 for a string.
If your table is insert-heavy and you see index fragmentation, consider time-ordered UUID v7 instead of v4 for better B-tree locality.
Keep the canonical lowercase, hyphenated form consistent across your codebase so string comparisons and lookups match.

AI Summary

Universally unique identifiers on demand.

Example Concepts

3f2504e0-4f89-41d3-9a0c-0305e82c3301

9a7b3c1d-2e4f-4a6b-8c9d-0e1f2a3b4c5d

16fd2706-8baf-433b-82eb-8c7fada847da

c73bcdcc-2669-4bf6-81d3-e4ae73fb11fd

d9428888-122b-11e1-b85c-61cd3cbb3210

f47ac10b-58cc-4372-a567-0e02b2c3d479

7c9e6679-7425-40de-944b-e07fc1f90ae7

550e8400-e29b-41d4-a716-446655440000

1b9d6bcd-bbfd-4b2d-9b5d-ab8dfbbd4bed

a3bb189e-8bf9-4888-9912-ace4e6543002

Target Use Cases

Use Case 1

Primary keys for database rows that need to be unique across shards or services.

Use Case 2

Stable resource identifiers in REST and GraphQL APIs that shouldn't expose sequential counts.

Use Case 3

Correlation, request, or trace IDs threaded through logs to follow one call across services.

Use Case 4

Idempotency keys so a retried POST doesn't create a duplicate record.

Use Case 5

Object keys for files in S3-style storage where names must not collide.

Use Case 6

Message or event IDs in a queue or pub/sub system for deduplication.

Use Case 7

Seeding test fixtures and database migrations with realistic-looking unique values.

Use Case 8

Device, session, or installation identifiers generated on the client.

Use Case 9

Tenant or namespace IDs in a multi-tenant application.

Use Case 10

One-off unique tokens for demos, prototypes, or filling a sample dataset.

✓ Best Practices

Pick v4 for general unique IDs and v7 when you need keys that also sort by creation time.

Use your database's native UUID type and let it store the 16-byte binary form.

Normalize to canonical lowercase hyphenated strings everywhere in your application.

Generate security-sensitive tokens with a cryptographic RNG on the server, not a convenience tool.

Add explicit timestamp columns rather than inferring time from the identifier.

Validate and parse UUIDs at trust boundaries before using them as keys.

Prefer UUIDs over auto-increment integers when IDs are created in distributed or offline contexts.

Keep one canonical string representation to avoid duplicate-key bugs.

Index UUID columns deliberately and monitor fragmentation on high-insert tables.

Document which UUID version your system uses so future developers don't mix schemes.

✗ Common Mistakes

Treating a v4 UUID as a secret — it's unguessable in practice but is meant to be unique, not a cryptographic credential.

Storing UUIDs as VARCHAR(36) when a native 16-byte uuid type is available, wasting space and slowing indexes.

Assuming UUIDs sort chronologically; v4 is random and has no embedded timestamp.

Mixing cased and hyphen-stripped forms so the same ID is stored two different ways and lookups miss.

Using sequential integer IDs in public URLs to avoid UUIDs, then leaking row counts and enabling enumeration.

Expecting collisions at small scale — they're effectively impossible until astronomically large counts.

Generating millions of v4 keys for a write-heavy table and then blaming the database for index bloat instead of switching to v7.

Relying on this in-browser tool for production security tokens instead of a vetted server-side generator.

Forgetting to add a created_at column and later being unable to order records by creation time.

Hand-editing a UUID and accidentally breaking the version or variant nibble so it's no longer valid.

Professional Tips

Store UUIDs in a native uuid/uniqueidentifier column type when your database has one — it uses 16 bytes instead of 36 for a string.
If your table is insert-heavy and you see index fragmentation, consider time-ordered UUID v7 instead of v4 for better B-tree locality.
Keep the canonical lowercase, hyphenated form consistent across your codebase so string comparisons and lookups match.
Don't use a client-side convenience UUID as a security token; generate session and auth tokens server-side from a cryptographic source.
UUID v4 carries no creation time, so add a separate created_at column if you need ordering or auditing.
When exposing IDs in URLs, remember UUIDs are 36 characters — fine, but longer than a short slug, so plan your routes accordingly.
Validate incoming UUID strings with a regex or your platform's parser before trusting them as keys.
Use UUIDs as keys when records are created across multiple services or offline clients that can't share a sequence.
Avoid uppercasing or stripping hyphens in storage unless every reader normalizes the same way.
For URL-friendliness, you can Base64- or Base32-encode the 16 raw bytes, but store the canonical form as the source of truth.

Frequently Asked Questions

Is this UUID generator free?

Yes. You can generate as many UUIDs as you want for free, with no account, no limits, and no watermark. They're free to use in both personal and commercial projects.

What version of UUID does it create?

It produces version 4 UUIDs, the random variant defined by RFC 4122. You can recognize them because the digit after the second hyphen is always 4 and the fourth group starts with 8, 9, a, or b.

How many UUIDs do I get per click?

Each click returns a batch of ten freshly generated UUIDs. Click Generate more to get another ten, as often as you need.

What's the difference between a UUID and a GUID?

They're the same thing. GUID (globally unique identifier) is Microsoft's name for the format; UUID (universally unique identifier) is the term used by RFC 4122 and most other ecosystems.

Will two UUIDs ever collide?

Practically never. A v4 UUID has 122 random bits, so you would need to generate billions of them before the probability of even a single duplicate becomes meaningful. They're safe to use as keys without a coordinating server.

Can I use v4 UUIDs as database primary keys?

Yes, and it's a common pattern, especially in distributed systems. Store them in a native uuid column when possible. If your table is very insert-heavy, UUID v7 offers better index locality because it's time-ordered.

What's the difference between v4 and v7?

v4 is fully random with no embedded time. v7 places a millisecond timestamp in the high bits so the values sort roughly by creation time, which improves B-tree index performance on write-heavy tables. v4 is simpler and more universal.

Are these UUIDs cryptographically secure?

They're suitable for unique identifiers, fixtures, and correlation IDs, but a browser convenience tool isn't the right source for security secrets. Generate session tokens, API keys, and similar credentials with a cryptographic RNG on the server.

Are the generated UUIDs sent to a server?

No. Everything is generated locally in your browser. The values are never transmitted, logged, or stored anywhere, so they stay completely private to you.

What does the 8-4-4-4-12 format mean?

It describes the grouping of the 32 hexadecimal digits: eight, then four, then four, then four, then twelve, separated by hyphens — 36 characters in total including the hyphens.

Should I store the hyphens?

Storing the canonical hyphenated form is the safest default so every reader agrees on the representation. If you store the raw 16 bytes in a native type, the hyphens are just a display convention applied when you format it.

Can I generate UUIDs offline?

Once the page is loaded, generation happens entirely in your browser, so it keeps working without a network connection.