UUID Generator
Generate UUID v4 identifiers for databases, APIs, and distributed systems.
Click Generate to create UUIDs.
What Is a UUID?
A UUID (Universally Unique Identifier) is a 128-bit label used for unique identification in computer systems. The term GUID (Globally Unique Identifier) is often used interchangeably, particularly in Microsoft ecosystems. UUID v4 is randomly generated, providing approximately 5.3 × 10³⁶ possible values — making collisions virtually impossible. Our free UUID generator online creates cryptographically secure UUIDs right in your browser.
UUID vs Auto-Increment IDs
UUID
- Unique across all systems, databases, and tables
- No central coordination needed
- Safe in distributed and offline-first architectures
- 128-bit, takes more storage
Auto-Increment ID
- Unique only within a single table
- Requires sequential generation
- Collisions when merging databases
- 32/64-bit integer, compact storage
Why UUID v4 Is Used
- Distributed Databases — Generate unique keys offline without conflicts when syncing.
- API Design — Use UUIDs as resource identifiers that can't be enumerated or guessed.
- Microservices — Each service generates its own IDs without a central authority.
- Event Sourcing — Unique event IDs that work across event stores and message buses.
- Client-Side Generation — Create IDs on the client before server submission (optimistic UI).
Is UUID Safe?
UUID v4 uses random number generation. Our tool uses the Web Crypto API
(crypto.randomUUID()), which is cryptographically secure.
This means your generated UUIDs are not predictable and are suitable for security-sensitive
applications like session tokens, API keys, and resource identifiers.
How to Generate UUIDs
Set the quantity (1–50) and click Generate. Each UUID is displayed in a separate row with its own copy button. Use Copy All to copy every UUID to your clipboard at once — one per line, perfect for batch inserts or API payloads.
A Universally Unique Identifier (UUID), standardized by RFC 4122 and RFC 9562, is a 128-bit label used to uniquely identify information across computer systems without requiring central coordination. UUID Version 4 generates identifiers using pseudo-random numbers: out of the 128 bits, 122 bits are purely random, 4 bits designate the version (0100 for v4), and 2 bits designate the variant (10 for RFC 4122). Because there are 2^122 (approximately 5.3 x 10^36) possible UUID v4 values, the mathematical probability of a duplicate collision is so infinitesimally low that it is practically zero: generating one billion UUIDs every second for 100 years would only yield a one-in-a-billion chance of collision. UUIDs are the de facto standard for primary keys in distributed databases (such as CockroachDB, Cassandra, and MongoDB), microservice request tracing correlation IDs, session tokens, and RESTful resource endpoints. WebUtil allows you to generate single or bulk UUID v4 identifiers instantly in your browser with one-click copying, uppercase/lowercase options, and zero server requests.
How to Do This in Code
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UUID Generator FAQ
What is a UUID v4 and how is it generated?
UUID v4 is a 128-bit universally unique identifier created from cryptographically random numbers. It is formatted as 32 hexadecimal characters in five hyphen-separated groups: 8-4-4-4-12.
What are the odds of two UUID v4 values colliding?
The probability is approximately 1 in 2^122. You would need to generate over 1 billion UUIDs per second for decades before expecting a single accidental collision.
Why use UUIDs instead of auto-incrementing integers for database IDs?
UUIDs allow distributed servers and microservices to generate IDs independently without a central database lock, prevent enumeration attacks, and make merging databases seamless.
What is the difference between a UUID and a GUID?
GUID (Globally Unique Identifier) is Microsoft's implementation of the RFC 4122 UUID standard. The two terms are practically synonymous in software development.
Can I bulk generate hundreds of UUIDs at once?
Yes. You can select the count in the generator controls and copy all generated UUIDs formatted as a clean list with a single click.