Are UUIDs really unique?

A v4 UUID has 122 random bits, so the chance of generating the same value twice is negligible for any realistic volume. Version 7 combines a timestamp with random bits, which keeps collisions just as unlikely.

What is the difference between a UUID and a GUID?

GUID is Microsoft's name for the same 128 bit identifier. The values generated here work wherever a GUID is expected; only the casing or braces may differ.

Is UUID v7 safe to expose publicly?

It is unique and hard to guess in its random part, but its first 48 bits reveal the creation time to the millisecond. If that is sensitive, use v4.

Can I generate more than 1,000 UUIDs?

One click produces at most 1,000. Click Generate again for another batch.

Can I get uppercase UUIDs?

The tool outputs lowercase, the canonical form. Most systems compare UUIDs case insensitively; if yours does not, convert the copied list in your editor.

Is anything sent to a server?

No. The identifiers are generated in your browser via WebAssembly and are never transmitted or stored.

UUID Generator: v4 and v7, up to 1000

This UUID generator creates universally unique identifiers in the two versions developers actually use today: version 4, fully random, and version 7, which starts with a timestamp so identifiers sort by creation time. Generate one or up to 1,000 in a single click and copy the list. The identifiers are produced by the Rust uuid crate compiled to WebAssembly and seeded from your browser's cryptographic random generator, so nothing is requested from a server.

How to generate UUIDs

Choose the version: v4 (selected by default) or v7.
Set the Count between 1 and 1000.
Click Generate. The list appears with one UUID per line, and the label below it shows which version was produced.
Click the copy button to copy the whole list to the clipboard.

A first v4 UUID is generated automatically when the page loads, so if you only need one, it is already there. Values above 1,000 are capped at 1,000.

UUID v4 or v7: which one to use

	UUID v4	UUID v7
Content	122 random bits	48 bit Unix timestamp in milliseconds, then random bits
Sort order	Random	Roughly by creation time
Reveals creation time	No	Yes, to the millisecond
Best for	Tokens, public IDs, anything that must not leak timing	Database primary keys, event IDs, logs

Why prefer UUID v7 for a database primary key? Random v4 values land anywhere in a B-tree index, so every insert touches a different page. Version 7 values increase over time, so new rows are appended near the end of the index, which keeps inserts cheaper and makes "newest first" queries simpler. The batch here is ordered: within one click, each v7 UUID sorts after the previous one, even when several are created in the same millisecond.

Prefer v4 when the identifier is visible to users or other parties and the creation time is private information, for example in password reset links or invitation codes.

Output format

Each UUID is the standard 36 character form: 32 lowercase hexadecimal digits in groups of 8, 4, 4, 4 and 12, separated by hyphens, for example 3f8e2a6c-9b41-4d7e-a2c5-1e0f6b9d8c47. The first digit of the third group is the version (4 or 7). The tool does not add braces, uppercase letters or quotes. If a system expects {UPPERCASE} GUIDs, transform the copied text in your editor.

Typical uses

Seeding test data: paste 50 or 500 UUIDs into fixtures, CSV imports or SQL INSERT statements.
Database migrations: generate v7 keys to backfill a new primary key column in creation order.
Configuration and infrastructure: unique IDs for feature flags, tenants, message queues or idempotency keys.
Documentation and mock APIs: realistic identifiers for examples and OpenAPI specs.

Compared with the command line and databases

On macOS and Linux, uuidgen prints a random UUID (macOS prints it in uppercase). PostgreSQL offers gen_random_uuid() for v4 and, since version 18, uuidv7(). Those are the right choice inside scripts and queries. This page is faster when you need a ready to paste list, a quick v7 for a test, or a machine where you cannot install anything.

Limits

Versions 4 and 7 only: v1, v3, v5 and the nil UUID are not generated.
No validation or parsing: the tool generates identifiers, it does not inspect existing ones.
1,000 per click: click again for more. Each click produces new values.

Privacy: generated locally, never logged

A UUID used as a session ID, an API key component or an invitation token must not be known to anyone else. An online generator that creates IDs on its server could, in principle, record them. Here generation runs in a WebAssembly module in your tab, using the browser's cryptographic random source, and no request is made when you click Generate. You can confirm this in the Network tab of your browser's developer tools.

Frequently asked questions

Are UUIDs really unique?: A v4 UUID has 122 random bits, so the chance of generating the same value twice is negligible for any realistic volume. Version 7 combines a timestamp with random bits, which keeps collisions just as unlikely.
What is the difference between a UUID and a GUID?: GUID is Microsoft's name for the same 128 bit identifier. The values generated here work wherever a GUID is expected; only the casing or braces may differ.
Is UUID v7 safe to expose publicly?: It is unique and hard to guess in its random part, but its first 48 bits reveal the creation time to the millisecond. If that is sensitive, use v4.
Can I generate more than 1,000 UUIDs?: One click produces at most 1,000. Click Generate again for another batch.
Can I get uppercase UUIDs?: The tool outputs lowercase, the canonical form. Most systems compare UUIDs case insensitively; if yours does not, convert the copied list in your editor.
Is anything sent to a server?: No. The identifiers are generated in your browser via WebAssembly and are never transmitted or stored.

Related tools: read the timestamp of an event with the Unix timestamp converter, derive a stable identifier from text with the SHA-256 hash generator, or fill a mock dataset with the Lorem Ipsum generator.