A UUID (Universally Unique Identifier) is a 128-bit value used to uniquely identify information in computer systems without requiring a central registration authority. UUIDs are also known as GUIDs (Globally Unique Identifiers) in Microsoft ecosystems. The standard format is a 32-character hexadecimal string displayed as five groups separated by hyphens in the pattern 8-4-4-4-12, for example: 550e8400-e29b-41d4-a716-446655440000. UUIDs are defined by RFC 4122 and are widely adopted across databases, APIs, distributed systems, and software development.
Version 1 (v1) UUIDs are generated from a timestamp and the MAC address of the machine. They guarantee uniqueness but can reveal information about when and where they were created. Version 4 (v4) UUIDs are generated using random or pseudo-random numbers, making them the most widely used version for general-purpose applications. They provide no information leakage and are simple to generate. Version 5 (v5) UUIDs are generated by hashing a namespace identifier and a name using SHA-1, producing a deterministic result — the same input always yields the same UUID.
This generator creates version 4 UUIDs using your browser's built-in crypto.randomUUID() API, which produces cryptographically strong random values. Every UUID generated is statistically unique. The probability of generating two identical v4 UUIDs is astronomically low — you would need to generate approximately 2.71 quintillion UUIDs to have a 50% chance of a single collision. For practical purposes, v4 UUIDs can be treated as globally unique without coordination.
UUIDs are used as database primary keys in systems like PostgreSQL, MySQL, and MongoDB where auto-incrementing integers are unsuitable or expose internal ordering. They serve as session identifiers in web applications, ensuring each user session is uniquely tracked. In distributed systems and microservice architectures, UUIDs allow multiple nodes to generate unique identifiers independently without conflicts. They are also used for API request IDs, file naming, message queue deduplication, correlation IDs in logging, and temporary resource identifiers.
Click Generate to create a single UUID, or click on the displayed UUID to copy it to your clipboard. Use the Uppercase option to output the UUID in uppercase hex characters, or Without hyphens to produce a compact 32-character string. For batch generation, enter a quantity (up to 500) in the bulk section and click Generate Bulk. Click any row in the bulk list to copy that UUID, or use Copy All to copy the entire list as newline-separated text.
This tool runs 100% client-side in your browser using the Web Crypto API. No UUIDs are sent to any server, stored, or logged. Generation happens entirely on your device with cryptographically secure randomness. There are no usage limits, no accounts required, and no telemetry. It is safe to use for generating identifiers for production systems, security tokens, and sensitive applications.