About

In distributed software architecture, the need for unique identification without central coordination is paramount. The Universally Unique Identifier (UUID) standard, defined by RFC 4122, provides a 128-bit number used to identify information in computer systems. Unlike simple auto-incrementing integers, UUIDs allow multiple independent systems to generate keys without risk of duplication. This tool allows developers to generate Version 1 (timestamp-based) and Version 4 (random) UUIDs, offering formatting options for SQL databases, JSON APIs, and legacy Microsoft GUID systems.

Accuracy and randomness are critical. A weak random number generator can lead to ID collisions, causing catastrophic data integrity failures in database merging or session management. This utility leverages the browser's cryptographic API (crypto.getRandomValues) to ensure sufficient entropy. Furthermore, for database administrators, the tool provides bulk generation with pre-formatted SQL INSERT statements, streamlining the creation of test datasets.

Formulas

The structure of a standard UUID involves specific bit manipulations to indicate the version and variant. For a Version 4 UUID, the schema is:

UUID = xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx

Where M represents the version (4) and N represents the variant.

{

M = 0100 (Binary for 4)N = 10xx (Variant 1)

The probability p of a collision in a Version 4 UUID space, given n generated IDs, is calculated using the Birthday Paradox approximation:

p ≈ 1 − exp−n²2 × 2¹²²

This implies that to reach a 50% chance of collision, one would need to generate approximately 2.3 × 10¹⁸ UUIDs.

Reference Data

Parameter	Version 1 (Time-based)	Version 4 (Random)	Details
Basis	Timestamp + MAC Address	Random Numbers	Source of uniqueness.
Entropy	14 bits (Clock Sequence)	122 bits	Random component size.
Layout	Time-Low-Time-Mid-Ver	Random-Random-Ver	Structure of the 32 hex digits.
Collision Risk	Near Zero (if MAC unique)	1 in 2.7 × 10¹⁸	Probability of duplicate IDs.
Use Case	Ordered rows, traceable origin.	Primary Keys, Session IDs.	Recommended application.
RFC 4122	Compliant	Compliant	Standard adherence.
Bit Size	128 bits	128 bits	Total binary size.
Hex Length	32 chars	32 chars	Excluding hyphens.

Frequently Asked Questions

Version 4 UUIDs are completely random, which means they do not reveal any information about the generation time or the machine's MAC address (privacy). However, because they are random, they can cause index fragmentation in clustered databases compared to Version 1 or Version 7, which are time-ordered. Despite this, v4 is the industry standard for general-purpose unique keys due to its simplicity and lack of dependency on a central clock.

While this tool uses a cryptographically secure random number generator (CSPRNG), UUIDs themselves are not intended to be secret keys. They are designed for uniqueness, not unpredictability in a security context. Do not use a UUID as a password or a private encryption key.

Functionally, they are the same. GUID (Globally Unique Identifier) is a term used primarily in the Microsoft ecosystem, while UUID (Universally Unique Identifier) is the standard Open Software Foundation (OSF) term. Both are 128-bit numbers. Microsoft GUIDs are often displayed with curly braces, which this tool supports via the formatting options.

Select "SQL Insert" from the Output Format dropdown in this tool. It will wrap the generated UUIDs in standard SQL syntax (e.g., INSERT INTO table (id) VALUES ('uuid');), ready to be executed in MySQL, PostgreSQL, or SQL Server.

Yes, for all practical purposes. The collision probability is so low that if you generated one billion UUIDs every second for the next 100 years, the probability of creating just one duplicate would be about 50%. This is considered "effectively zero" in engineering.