UUID Generator

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What this tool does

This tool generates one or many UUIDs at once in version 4 (random), version 7 (timestamp-ordered), version 1 (legacy timestamp-based), or the all-zero nil UUID, with optional uppercase, hyphen-free, braced, or urn:uuid: formatting, and can also parse any existing UUID to show its version, variant, and embedded timestamp.

How It Works

A UUID is 128 bits laid out in a fixed pattern: a few of those bits are reserved to mark the version and variant, and the rest carry either random data or, for version 1 and version 7, a timestamp. This tool fills the random bits using your browser's cryptographically secure random number generator, computes the timestamp bits directly from the current time for version 1 and version 7, sets the version and variant bits to the correct fixed values, and writes the result out in the standard 8-4-4-4-12 hexadecimal grouping before applying any formatting you chose. Inspecting a UUID simply reverses this: it reads the version and variant bits directly, and for version 1 or 7 decodes the timestamp bits back into a calendar date.

Problems it solves

• Generating a batch of unique IDs for database seeding, test fixtures, or placeholder data all at once.
• Choosing a UUID version that sorts well as a database primary key instead of defaulting to plain random v4.
• Checking which version a UUID you found in code or a database actually is, and roughly when it was created if it is a v1 or v7.
• Matching the exact formatting (braces, uppercase, no hyphens, urn: prefix) that a particular system or API expects.

Frequently asked questions