UUID Generator
Generate cryptographically random UUID v4 or time-ordered UUID v7 in bulk, in your browser.
Written by Golam Rabbani, Founder & Lead Engineer
How to use this uuid generator
- Choose a UUID version from the "UUID Version" dropdown — v4 (random) or v7 (time-ordered).
- Set the Count field to how many UUIDs you need (1 to 200).
- Click Generate to produce the batch.
- Scan the result list to confirm the output looks correct.
- Click "Copy all" to write every UUID to your clipboard, one per line.
About this uuid generator
The UUID generator produces one or more universally unique identifiers in the standard 36-character canonical form: eight hex digits, a hyphen, four, a hyphen, four, a hyphen, four, a hyphen, twelve — for example `f47ac10b-58cc-4372-a567-0e02b2c3d479`. Each UUID is a 128-bit value, and the format is defined by RFC 4122 (v4) and the newer RFC 9562 (v7).
Version 4 fills all non-reserved bits with cryptographically random data using `crypto.randomUUID()` or `crypto.getRandomValues()`. Because the randomness covers roughly 122 bits, the chance of two v4 UUIDs colliding is astronomically small — generating a billion per second for a century would still leave the probability of a single collision near zero. Version 7 replaces the leading 48 bits with the current Unix epoch in milliseconds, followed by a version nibble, 12 random bits, a variant marker, and 62 more random bits. The timestamp prefix means v7 UUIDs sort in insertion order, which produces friendlier B-tree behavior in database indexes compared to the scattered distribution of v4.
For example, a v4 result might be `f47ac10b-58cc-4372-a567-0e02b2c3d479` (fully opaque) while a v7 result like `018f6c0a-d2b5-7c00-9c1f-31a1c1a2b3c4` encodes the generation timestamp in its first 12 hex characters. All IDs are generated locally in your browser and are never transmitted to or logged by any server.
FAQ
- What is a UUID generator and when should I use one?
- A UUID generator creates universally unique 128-bit identifiers in the standard 8-4-4-4-12 hex format. Use them wherever you need a collision-resistant ID without a central counter — distributed systems, database primary keys, session tokens, file names, and API resources are common cases.
- What is the difference between UUID v4 and v7?
- v4 is fully random (122 random bits) and carries no meaning about when it was created. v7 embeds a 48-bit millisecond timestamp in the leading bits, so v7 IDs sort chronologically. Choose v4 when you need an opaque ID; choose v7 when the IDs will be stored in a database index and sequential ordering matters for write performance.
- Does UUID v7 leak my creation timestamp?
- Yes. The first 48 bits of a v7 UUID encode the Unix epoch in milliseconds, so anyone who sees the ID can determine when it was generated to within one millisecond. If exposing creation time is a privacy concern, use v4 instead.
- Why use UUIDs instead of auto-increment integers?
- Auto-increment IDs require a central authority (the database sequence), which creates a bottleneck in distributed systems and exposes record counts to callers. UUIDs are generated independently on any node without coordination, and they reveal no information about table size or insertion order (v4) or only time (v7).
- How likely is a UUID v4 collision?
- Extremely unlikely. With 122 bits of randomness, you would need to generate roughly 2.7 × 10¹⁸ UUIDs before the probability of a single collision reaches 50%. At a rate of one billion per second that would take about 86 years.
- What is the maximum number of UUIDs I can generate at once?
- The tool supports batches of 1 to 200 UUIDs per click. For larger batches, click Generate again or use a server-side library in your application code.