Online UUID and GUID Generator

Generate one or many UUID identifiers with configurable casing and formatting. Available UUID versions support common needs such as random identifiers, time-ordered records and compatibility with systems that refer to UUIDs as GUIDs.

UUIDs are useful for distributed identifiers because generation does not require a central numeric sequence. Choose the version according to privacy, ordering and interoperability requirements.

Instructions

How to generate UUIDs

Select the desired version, choose the quantity and click Generate. New UUIDs are generated automatically when you change the version, quantity or format. Use the copy button next to each UUID to copy it individually, or Copy all to copy the whole list separated by line breaks.

Format options

UPPERCASE displays the hexadecimal characters in uppercase letters — useful for compatibility with systems that are case-sensitive. No hyphens removes the separators, producing a continuous 32-character string, a common format in databases that store UUIDs as CHAR(32).

What is a UUID

A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier) in the Microsoft ecosystem, is a 128-bit identifier standardized by RFC 4122 and revised by RFC 9562 (2024). Its main characteristic is the ability to be generated in a decentralized way, without the need for a central coordination server, with a statistically negligible probability of collision.

UUIDs are widely used as primary keys in databases, session identifiers, correlation tokens in distributed logs and resource IDs in REST APIs. The canonical format consists of 32 hexadecimal digits separated by hyphens in groups of 8-4-4-4-12, totaling 36 characters.

UUID v4 — random

The most used in practice. It generates 122 bits of cryptographic randomness (the remaining 6 bits are reserved for version and variant). It is suitable for the vast majority of use cases, with a probability of collision so low that it can be ignored in practice — about 2.7 trillion UUIDs would be needed to reach a 50% chance of collision.

UUID v7 — time-sortable

Introduced by RFC 9562 in 2024, UUID v7 embeds the first 48 bits as the Unix timestamp in milliseconds, making it naturally sortable by creation time. This solves a classic UUID v4 problem in databases: random insertions cause fragmentation of B-tree indexes. With v7, sequentially inserted records stay adjacent in the index, significantly improving write performance.

UUID v1 — timestamp and node based

UUID v1 uses the timestamp with 100-nanosecond precision counted from October 15, 1582 (the date the Gregorian calendar was adopted), combined with a node identifier (originally the machine's MAC address). Since it does not have access to the MAC in the browser, this tool uses random bytes as the node, keeping the temporal structure of the format.