UUID / GUID Generator - Create Random UUIDs Online

Generate random UUIDs and GUIDs instantly with our free online UUID Generator. Create RFC 4122-compliant UUID v4 (random), UUID v7 (time-ordered), and NIL UUIDs in any quantity - all produced locally in your browser using the Web Crypto API for cryptographically secure randomness and complete privacy.

Our UUID generator uses crypto.getRandomValues instead of Math.random() , so every identifier is unpredictable and safe to use for database primary keys, API tokens, distributed systems, and session IDs. Customize the version, quantity, case, hyphens, and GUID brace formatting.

Live Example

Here is sample output for both random and time-ordered variants. Notice the version digit (the first hex of the third group) is 4 for v4 and 7 for v7:

Request

Generate 3x UUID v4
Generate 1x UUID v7

Generated UUIDs

c3a9c4f1-8b2e-4d77-9a01-2f5e6a7b8c9d
7e1d3b5a-0c64-4f2a-bd10-6a8c9e0f1a2b
0b9f2c4d-7e8a-4310-9b6c-3d5e8f1a2b3c

01923f7e-7b4d-7a01-9c2e-4f5a6b8c0d1e   (v7: sorts after older v7s)

Key Features

Multiple Versions: Generate UUID v4 (fully random), UUID v7 (timestamp-sortable), or the special NIL UUID.
Cryptographically Secure: Powered by the Web Crypto API ( crypto.getRandomValues ) - never Math.random() .
Bulk Generation: Create up to 500 unique identifiers in a single click.
Flexible Formatting: Toggle uppercase hex, remove hyphens for compact strings, or wrap values in braces for Microsoft-style GUIDs.
RFC 4122-Compliant: Correct version and variant bits are always set, so UUIDs validate in any library.
One-Click Copy & Download: Copy to clipboard or download all generated UUIDs as a text file.
100% Private: All generation runs in your browser - nothing is sent to a server.

How to Use the UUID Generator

Choose a UUID version (v4 random, v7 time-ordered, or NIL).
Set how many UUIDs you need using the quantity slider (default: 1).
Toggle formatting options: uppercase, hyphens, and braces (GUID style).
Click "Generate" to create your identifiers.
Click "Copy" or "Download" to save the results.

What Is a UUID?

A UUID (Universally Unique Identifier), also called a GUID (Globally Unique Identifier), is a 128-bit identifier standardized in RFC 4122 . It is most often shown as a 36-character hexadecimal string grouped as 8-4-4-4-12 , for example 550e8400-e29b-41d4-a716-446655440000 . Because the 128-bit space is astronomically large, randomly generated UUIDs are unique in practice without any central coordination, which makes them ideal primary keys, API tokens, and correlation IDs.

The hyphenated layout maps directly onto the UUID's internal fields. The 13th hex digit encodes the version , and the first digit of the fourth group encodes the variant , so any standards-compliant parser can tell a v4 from a v7 at a glance.

UUID Versions Explained

UUID v4 (Random): 122 bits of randomness (except the fixed version and variant bits). The go-to choice when you only need uniqueness and don't care about ordering. Collision probability is negligible - about 1 in a billion after generating 100 trillion v4 UUIDs.
UUID v7 (Time-ordered): Embeds a millisecond Unix timestamp in the first 48 bits, followed by random bits. Newer UUIDs sort after older ones, which keeps database indexes compact and range queries fast. Recommended for new database primary keys.
NIL UUID: The reserved all-zeros value 00000000-0000-0000-0000-000000000000 , used as a sentinel or placeholder meaning "no identifier assigned".

Collision Probability and When to Use UUIDs

Because a UUID v4 carries 122 bits of randomness, the chance of a collision is vanishingly small. The classic birthday-paradox math says you would need to generate around 2.71 × 10¹⁸ UUIDs before reaching even a 50% chance of a single duplicate — roughly a billion generated IDs every second for over 85 years. In practice, that means randomly generated UUIDs are safe to use as unique keys with no central coordinator, which is exactly why they power database primary keys, API tokens, and correlation IDs across distributed services.

Choosing the right version matters. Use v4 when you only need uniqueness. Use v7 for new database primary keys: because each value starts with a millisecond timestamp, rows insert in sorted order, keeping B-tree indexes compact and range queries fast. NIL is a sentinel meaning "no value." UUIDs are identifiers, not secrets — they are predictable enough to enumerate in some versions, so never use one as a password; for secrets, use the Password Generator.

Common Errors and How to Fix Them

UUIDs fail validation: Confirm the version/variant bits. This tool always emits RFC 4122-compliant values; a failure usually means a hand-edited or truncated string.
Duplicates in bulk output: Extremely unlikely with v4/v7. If you see exact repeats, you are likely copying a cached result — regenerate.
Database index bloat with v4: Random v4 values fragment B-tree indexes. Switch to v7 for new primary keys so inserts stay ordered.
System rejects hyphens or case: Toggle the uppercase and hyphens options to match the consumer's expected format, or wrap in braces for Microsoft GUID style.

Frequently Asked Questions

1Is this UUID generator secure?

Yes. UUIDs are generated using the Web Crypto API (crypto.getRandomValues), which provides cryptographically secure randomness. We never use Math.random(), which is predictable and unsafe for identifiers used in security-sensitive contexts.

2Are my generated UUIDs sent to a server?

No. All generation happens entirely in your browser. Your UUIDs never leave your computer, so they remain completely private.

3What is the difference between UUID v4 and UUID v7?

UUID v4 is fully random. UUID v7 encodes the current Unix timestamp in its leading bits, so values generated over time are sortable, which improves database index locality and query performance.

4What is a NIL UUID?

The NIL UUID is the special all-zeros UUID (00000000-0000-0000-0000-000000000000). It is commonly used as a sentinel value to represent the absence of an identifier.

5Are the generated UUIDs RFC 4122-compliant?

Yes. The correct version and variant bits are always set, so the generated UUIDs validate in any standards-compliant library or database.

6Is a UUID the same as a GUID?

Practically yes. GUID (Globally Unique Identifier) is Microsoft's term for a UUID. The brace-wrapped format ({...}) is the conventional GUID string representation used in the Microsoft ecosystem.

7Can two randomly generated UUIDs collide?

In practice, no. A UUID v4 has 122 random bits. The probability of a collision is negligible: you would need to generate over 100 trillion v4 UUIDs to reach roughly a one-in-a-billion chance of any duplicate. For this reason random UUIDs are safely used as unique database keys.

8How do I generate a UUID in JavaScript, Node.js, or Python?

In modern JavaScript and Node.js use crypto.randomUUID(), which returns a standards-compliant v4 string. In Python use the uuid module: import uuid then uuid.uuid4(). This tool generates them in bulk in your browser so you can copy a batch without writing any code.