🆔 UUID Generator
Generate random version 4 UUIDs instantly.
What is this tool?
The UUID Generator is a free online tool that creates universally unique identifiers (UUIDs) with a single click. UUIDs are 128-bit numbers used to uniquely identify information in computer systems, databases, and distributed applications without requiring a central coordinating authority. A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier) in Microsoft ecosystems, is a 36-character string formatted as five groups of hexadecimal digits separated by hyphens: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx. The M indicates the version (4 for random UUIDs), and N encodes the variant. With 122 bits of randomness in version 4, the probability of two generated UUIDs being identical is astronomically small, making collisions practically impossible. UUIDs are used everywhere in modern software development: as database primary keys, session identifiers, API tokens, file names, message IDs, and more. They eliminate the need for a central ID authority, making them ideal for distributed systems. This generator creates cryptographically random version 4 UUIDs using your browser's secure random number generator, and can produce single UUIDs or batches of thousands at once.How it works
The generator creates version 4 UUIDs, which use random bits for most of the UUID. It uses the browser's crypto.getRandomValues() function, which provides cryptographically secure random numbers from the operating system's entropy pool. A version 4 UUID has the format: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx, where x is a random hexadecimal digit (0-9, a-f) and y is one of 8, 9, a, or b. The "4" in position 13 identifies it as version 4, and the y value (starting with 8, 9, a, or b) identifies the RFC 4122 variant. The remaining 122 bits are randomly generated, giving 2¹²² possible UUIDs. The collision probability is so low it can be ignored for all practical purposes. To have a 50% chance of a single collision, you would need to generate about 2.71 quintillion UUIDs. Even generating a billion UUIDs per second for 85 years, the collision probability remains negligible. The generator can produce UUIDs in uppercase or lowercase, with or without hyphens, and supports batch generation with configurable count.How to use
- Set the number of UUIDs to generate.
- Choose formatting options (case, hyphens).
- Click Generate to create the UUIDs.
- Copy individual UUIDs or all at once.
- Use them as unique identifiers in your projects.
Frequently Asked Questions
Frequently Asked Questions
What is a UUID used for?
UUIDs are used as unique identifiers in databases (primary keys), distributed systems (message/event IDs), APIs (request tracking), file storage (unique file names), and anywhere you need a unique reference without a central ID authority.
Are generated UUIDs truly unique?
Version 4 UUIDs have 122 bits of randomness, making collisions astronomically unlikely. The probability of a collision when generating 103 trillion UUIDs is still less than one in a billion. For all practical purposes, they are unique.
What is the difference between UUID and GUID?
They are essentially the same thing. UUID is the RFC 4122 standard name, while GUID is Microsoft's name for the same concept. The format and purpose are identical. GUIDs are typically written with braces, but the underlying data is the same.
Are the generated UUIDs cryptographically secure?
Yes. This generator uses crypto.getRandomValues(), which provides cryptographically secure random numbers from the operating system. The generated UUIDs are suitable for security-sensitive applications like session tokens and API keys.
Tips & Advice
UUIDs solve the problem of generating unique identifiers without coordination between systems. Version 4 (random) is the most common for general use because it requires no state and can be generated anywhere. Version 1 (time-based with MAC address) is useful when you need sortable IDs but reveals the generating machine's MAC address. Version 3 and 5 (name-based with hashing) produce deterministic UUIDs from a name string, useful when the same input should always produce the same UUID. For database primary keys, UUIDs avoid the sequential integer guessing vulnerability and work naturally with distributed databases. When using UUIDs in URLs, consider omitting hyphens or using base62 encoding to shorten them. Always use crypto.getRandomValues() for security-sensitive UUIDs, not Math.random().