Online UUID v4 generator
Your generated UUID version-4
Bulk UUID/GUID generator
Generate up to 1,000 UUIDs in v1, v4, v6, or v7, then copy or export your batch. For a larger workspace, open the bulk UUID generator with formatting and SQL export.
UUID in a nutshell
Because you might be a little confused about what a UUID actually is.
Version 1
A version 1 UUID is a unique identifier that is generated from a timestamp and the MAC address of the computer, ensuring uniqueness. However, because the MAC address is exposed, it poses potential privacy and security risks.Read more about v1
Version 4
A version 4 UUID is a unique identifier generated from random numbers. This makes it highly unlikely that any two UUIDs will ever be the same. The version 4 UUIDs generated by this site use a secure random number generator for maximum security.Read more about v4
Version 7
A version 7 UUID is a time-ordered UUID that encodes a Unix timestamp with millisecond precision in its most significant 48 bits. It uses 6 bits for version and variant, with the remaining 74 bits randomly generated. The sequential nature of UUIDv7 improves database performance by addressing the index locality issue, unlike the random UUIDv4.
Format reference: RFC 9562: Universally Unique Identifiers.
UUID v4 is a 128-bit identifier specified in RFC 9562. It has 122 random bits, four version bits, and two variant bits. The usual text representation has 32 hexadecimal digits and four hyphens, arranged in groups of 8-4-4-4-12.
UUID v4 contains random data rather than a timestamp. UUID v7 includes a 48-bit Unix timestamp in milliseconds, so it can be ordered by time. Neither format requires a central authority to generate IDs.
Yes. With independent uniform random values, there are 2^122 possible UUID v4 values. Collision probability depends on how many you generate, rather than being a fixed probability per system. Use database uniqueness constraints and handle conflicts.
Use an authentication library’s purpose-built token generator for credentials and session tokens. A UUID is an identifier; knowing it must not by itself grant access to a resource.
It can be. Random keys may have poorer B-tree insert locality than time-ordered keys. Whether UUID v7 improves performance depends on your database, indexes, and workload; benchmark your application rather than assuming a fixed speed improvement.
A UUID contains 16 bytes of binary data. The standard text form uses 36 characters. Actual row and index sizes depend on the database and column type. Use a native UUID type where available.
In a supported secure browser context, crypto.randomUUID() generates a UUID v4. This site uses the uuid library for its generators.