UUID Generator

A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier), is a 128-bit label used to uniquely identify objects in computer systems. The standard format is 32 hexadecimal digits in five groups separated by hyphens: 8-4-4-4-12. UUIDs are widely used as database primary keys, session tokens, file names, and anywhere a unique identifier is needed without central coordination.

UUID version 4 is randomly generated. Except for a few fixed bits (version and variant), all 122 bits are filled with cryptographically random data. This gives a collision probability so low it is effectively impossible in practice: generating 1 billion UUIDs per second would take about 85 years before a 50% probability of a single collision.

This tool uses the browser's built-in crypto.randomUUID() method, available in all modern browsers. It pulls entropy from the operating system's cryptographically secure random number generator (CSPRNG) - the same source used for TLS and key generation. No third-party library is involved.

The standard lowercase format (e.g. 550e8400-e29b-41d4-a716-446655440000) is the most widely accepted and is specified by RFC 4122. Uppercase is sometimes required by older Microsoft APIs. No-dashes format is useful for compact storage. Braces format ({550E8400-E29B-41D4-A716-446655440000}) is the classic Windows/COM GUID format.

Yes. UUID v4 is a common choice for distributed systems where you need unique IDs without a central sequence. The main tradeoff versus integer IDs is storage size (16 bytes vs 4-8 bytes) and random insertion order, which can fragment B-tree indexes. If insert performance is critical at high scale, consider UUID v7 (time-ordered) instead.

Yes. The standard UUID format uses only hexadecimal characters (0-9, a-f) and hyphens, all of which are URL-safe and require no percent-encoding. The no-dashes format is even more compact and equally safe in URLs.

Python's standard library includes a uuid module:

import uuid

# Generate a random UUID v4
my_uuid = uuid.uuid4()
print(str(my_uuid))  # e.g. 550e8400-e29b-41d4-a716-446655440000

# As a hex string without dashes
print(my_uuid.hex)

No third-party library needed. For bulk generation or formatted output, use the tool above.

Java includes java.util.UUID in the standard library:

import java.util.UUID;

// Generate a random UUID v4
UUID uuid = UUID.randomUUID();
System.out.println(uuid.toString());
// e.g. 550e8400-e29b-41d4-a716-446655440000

// Uppercase, no dashes
System.out.println(uuid.toString().replace("-", "").toUpperCase());