Free Online UUID Generator – Create UUIDs Instantly
A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify objects in computer systems without requiring a central authority. Our free online UUID generator lets you instantly create one or multiple UUIDs in v4 (random) or v1 (time-based) format for use in databases, APIs, and software development. Simply configure your options and get production-ready UUIDs in seconds.
Drag the slider to generate up to 20 UUIDs at once.
v4 uses random numbers; v1 is based on the current timestamp and a node identifier.
Toggle to display UUIDs in uppercase letters.
Uncheck to output UUIDs without hyphens (compact format).
Your results will appear here
How to Use This Calculator
1. Use the slider to choose how many UUIDs you want to generate (between 1 and 20). 2. Select your preferred UUID version — Version 4 for random UUIDs or Version 1 for time-based UUIDs. 3. Toggle the 'Uppercase Output' checkbox if you need UUIDs in capital letters. 4. Toggle 'Include Hyphens' on or off depending on whether you need the standard hyphenated format or a compact format. 5. Click 'Calculate' and your UUIDs will appear instantly in the results section. 6. Copy the results and paste them directly into your code, database, or documentation.
What Is a UUID?
A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier) in Microsoft ecosystems, is a 128-bit number represented as 32 hexadecimal digits, typically displayed in five groups separated by hyphens: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx. The letter M indicates the UUID version, and the bits of N indicate the variant.
UUID Versions Explained
Version 4 (Random)
UUID v4 is generated using random or pseudo-random numbers. Except for two bits used for the variant and four bits used for the version, all other bits are randomly generated. This makes v4 UUIDs statistically unique with an astronomically low probability of collision — ideal for most modern applications.
Version 1 (Time-Based)
UUID v1 incorporates the current timestamp (measured in 100-nanosecond intervals since October 15, 1582) along with a clock sequence and a node identifier (often derived from a MAC address). While v1 UUIDs are guaranteed to be unique across time on a single machine, they can expose information about when and where they were generated.
UUID Structure Breakdown
- Time Low (8 hex digits): The low field of the timestamp.
- Time Mid (4 hex digits): The middle field of the timestamp.
- Time High and Version (4 hex digits): The high field of the timestamp, multiplexed with the version number.
- Clock Sequence (4 hex digits): Helps avoid duplicates when the clock is set backwards.
- Node (12 hex digits): Spatially unique identifier (e.g., MAC address or random bytes).
When Should You Use UUIDs?
UUIDs are widely used in software engineering for primary keys in databases, session tokens, API request tracking, distributed system object identification, file naming to avoid conflicts, and more. Because they can be generated independently on any machine without coordination, they scale exceptionally well in distributed architectures.
Hyphenated vs. Compact Format
The standard UUID format includes four hyphens, resulting in 36 characters total. The compact format removes the hyphens, producing a 32-character hexadecimal string. Both represent the same value — the choice is purely a matter of system requirements or personal preference.