Developer Tools
UUID Generator
Generate cryptographically random UUID v4 values in bulk.
Generated identifiers (0)
About UUID Generator
A UUID is a 128-bit label that you can generate independently on any machine without coordination, which makes them ideal for database keys, request identifiers and idempotency tokens. The important property is randomness: identifiers generated from a weak source can collide or be predicted.
This generator draws bytes from the Web Crypto random source and applies the version 4 layout, setting the version and variant bits as the specification requires. You can generate up to 500 identifiers at once and paste them directly into code, fixtures or seed data.
How it works
- Random bytes come from crypto.getRandomValues, the operating system entropy source.
- The version nibble is set to 4 and the variant bits are set to the RFC 4122 pattern.
- Output can be formatted with braces, without hyphens, or in uppercase for legacy systems.
- Results are numbered so you can map them back to rows in your dataset.
- Copy the whole batch as plain text or as a JSON array.
- Uniqueness is probabilistic: 122 random bits mean collisions are not a practical concern.
Input and output
Accepts
A count between 1 and 500 and a formatting option.
Produces
A list of UUID version 4 values, copyable as text or JSON.
Privacy
Identifiers are generated with your browser crypto API. No identifier is recorded or transmitted.
UUID Generator FAQ
Is UUID version 4 really unique?
It is unique with extremely high probability rather than by construction. With 122 random bits you would need to generate about 2.7e18 identifiers before a 50 percent chance of any collision.
What is the difference between version 1 and version 4 UUIDs?
Version 1 embeds a timestamp and the generating machine MAC address, which leaks information. Version 4 is fully random and is the safer default.
Should I use UUIDs as database primary keys?
They are a good choice for distributed systems. Random UUIDs do fragment B-tree indexes though, so time-ordered variants such as v7 are often preferred for large tables.
Are capital letters valid in a UUID?
The specification is case-insensitive, so both forms are valid. Most tools and databases normalise to lowercase.
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