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UUID Generator

Generate v4 UUIDs for your apps.

Best for: Database primary keys, idempotency keys for safe retries, correlation/request IDs in logs, and unique file or object names.

Complete guide

Input

4aabb170-4573-443d-b698-8fb11daff09f
f3762532-75c7-46b5-8446-d96dad02656a
a02c9659-b993-4195-b7d0-68b170c1b436
60da6a07-cab3-471d-9a40-92eea2b4229b
69921629-a30d-40a7-936d-a8b165083def
How it's calculated & sources
The UUID Generator uses the standard method for this calculation. It runs entirely in your browser, so your inputs are never uploaded. Last reviewed June 2026.

Free & no sign-up · runs entirely in your browser. Results are estimates for general information, not professional advice — verify important decisions with a qualified expert. Last reviewed June 2026.

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Complete guide

Quick answers

Short, sourced answers to the questions people (and AI assistants) ask most.

What is UUID?
A UUID generator creates universally unique identifiers — 128-bit values shown as 32 hex digits in an 8-4-4-4-12 pattern — so you can mint IDs that stay unique without a central database or coordination.
Why does UUID matter?
Each value is effectively unique and can be used immediately as a key or identifier; v4 UUIDs are random, so they are not sortable by creation time.
How is UUID calculated?
A version-4 UUID is 122 random bits plus fixed version and variant markers, produced from your browser's cryptographically secure random source (crypto.getRandomValues). The probability that two v4 UUIDs ever collide is vanishingly small — you would need to generate billions per second for decades to have a meaningful chance.
What are common uuid mistakes?
Assuming UUIDs sort chronologically — v4 is random; use v7 or ULID when you need time ordering.
When should you use the UUID Generator?
Database primary keys, idempotency keys for safe retries, correlation/request IDs in logs, and unique file or object names.

What is the UUID Generator?

A UUID generator creates universally unique identifiers — 128-bit values shown as 32 hex digits in an 8-4-4-4-12 pattern — so you can mint IDs that stay unique without a central database or coordination.

How the UUID Generator works

A version-4 UUID is 122 random bits plus fixed version and variant markers, produced from your browser's cryptographically secure random source (crypto.getRandomValues). The probability that two v4 UUIDs ever collide is vanishingly small — you would need to generate billions per second for decades to have a meaningful chance.

UUID versions

v1Timestamp + node (MAC)Roughly
v3MD5 hash of a nameNo
v4RandomNo
v5SHA-1 hash of a nameNo
v7Unix time + randomYes

Worked example

3f2504e0-4f89-41d3-9a0c-0305e82c3301 Pattern: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx (the 4 marks version 4; y is 8, 9, a or b).

Key terms

Variant / version:
Fixed bits that mark the UUID layout and how it was generated.
ULID:
A 128-bit, lexicographically sortable, time-based alternative to UUIDv4.

Common mistakes to avoid

  • Assuming UUIDs sort chronologically — v4 is random; use v7 or ULID when you need time ordering.
  • Treating a UUID as a secret — it is an identifier, not a security token.
  • Storing as a 36-char string when a 16-byte binary column is smaller and faster.
  • Relying on the MAC address in v1, which can leak the host and is often disabled.

Detailed FAQ

Could two UUIDs ever be the same?

In theory yes, in practice effectively never for v4 — there are 2^122 possibilities, so collisions are astronomically unlikely for any realistic volume.

Are UUIDs random enough to be unguessable?

v4 uses a cryptographically secure RNG, so they are hard to guess, but never rely on that alone for security — treat them as identifiers, not passwords or tokens.

v4 or v7?

Use v4 for plain unique IDs; choose v7 when you want IDs that also sort by creation time (better database index locality).

Keywords: uuid, guid.

Sources: RFC 9562 — UUID (obsoletes RFC 4122), MDN — crypto.randomUUID()

Reviewed by the Free Tools Galaxy editorial team · Updated June 2026 · Calculated privately in your browser.

Frequently asked questions

Is the UUID Generator free to use?+

Yes. Every tool on Free Tools Galaxy is 100% free, runs in your browser and requires no signup.

How accurate is the UUID Generator?+

UUID Generator uses the standard uuid formula in double-precision arithmetic, so the same inputs always produce the same result and you can verify any figure by hand. It is an educational estimate — real-world outcomes depend on your actual rates, rules and assumptions.

Do you store my inputs?+

No. The UUID Generator runs entirely in your browser. Nothing is uploaded or saved to a server.

Can I use the UUID Generator on mobile?+

Yes — the interface is fully responsive and works on phones, tablets and desktops.

What are common mistakes to avoid?+

The most frequent mistake is mixing units. Double-check your inputs use a single, consistent unit before clicking Calculate.

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Title: I built/used this free uuid generator — instant, no signup

Body: Generate v4 UUIDs for your apps. Try it: https://freetoolsgalaxy.com/tools/uuid-generator
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UUID Generator on Free Tools Galaxy — Generate v4 UUIDs for your apps. https://freetoolsgalaxy.com/tools/uuid-generator
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# UUID Generator — the free tool I keep coming back to

Generate v4 UUIDs for your apps.

Try it: https://freetoolsgalaxy.com/tools/uuid-generator
Quora answer
The fastest way is to use a free in-browser uuid generator: https://freetoolsgalaxy.com/tools/uuid-generator. Generate v4 UUIDs for your apps.

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