# UUID v4 Generator – Bulk GUID Tool

> Bulk-generate 1–100 UUID v4 identifiers instantly with cryptographically secure randomness. Format options, copy-all, version table and honest collision math.

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# UUID v4 Generator

A UUID v4 is a 128-bit identifier built from 122 random bits, formatted as 8-4-4-4-12 hex digits — like `5e01f55d-68c5-40ea-acbd-2b286034272d`. This bulk generator mints 1–100 of them at a time using the Web Crypto API's cryptographically secure random number generator; nothing is logged, stored or reused.

## Your UUIDs one per line

5e01f55d-68c5-40ea-acbd-2b286034272d

Freshly minted server-side for this exact request. Load again for new values — or enable JavaScript to keep generating locally without reloads.

## How it works — and how unlikely a collision really is

Each identifier starts as 16 bytes from `crypto.getRandomValues()`, a CSPRNG seeded by the host OS. Two fields are then overwritten per ISO/IEC 9834-8 and RFC 9562: the *version* nibble becomes `4` (byte 6 high nibble) and the *variant* field becomes `10xx` (byte 8 top bits). That leaves exactly 122 random bits — the entire collision story below rests on those.

### The honest collision math

Birthday-bound math says you need about **√(2123 × ln 4) ≈ 2.7 × 1018** v4 UUIDs before the probability of even one duplicate reaches 50% — that's 2.71 quintillion. Generating a billion UUIDs per second, it would take roughly 85 years to reach coin-flip odds. At more realistic scale: minting 103 trillion UUIDs gives about a one-in-a-billion chance of any single collision. Duplicate risk is not zero, but treating v4 IDs as unique within a system is engineering-grade sound.

### UUID versions at a glance (per RFC 9562)

| Version | Source of bits | Typical use / caveat |
| --- | --- | --- |
| 1 | 60-bit Gregorian timestamp + node MAC address | Sortable-ish; leaks MAC & creation time |
| 2 | DCE security (POSIX UID/GID) | Rare; mostly historic |
| 3 | MD5 hash of a namespace + name | Deterministic; MD5 legacy |
| 4 | 122 random bits (this tool) | The default choice everywhere |
| 5 | SHA-1 hash of a namespace + name | Deterministic, stronger than v3 |
| 6 | v1 reordered for lexicographic sorting | New in RFC 9562; DB-friendly |
| 7 | Unix-ms timestamp + 74 random bits | New in RFC 9562; sortable & modern favorite |
| 8 | Vendor/experimental custom | Not guaranteed unique — read the spec |

Need unpredictable secrets instead of identifiers? Random tokens belong to the [password generator](https://itinsighthub.com/password-generator/); scheduling jobs that consume these IDs is the [cron generator's](https://itinsighthub.com/cron-generator/) job; log correlation pairs them naturally with the [Unix timestamp converter](https://itinsighthub.com/timestamp-converter/); and port numbers for the services emitting your events sit in the [common ports reference](https://itinsighthub.com/common-ports/).

## Frequently asked questions

**What is a UUID?**

A Universally Unique Identifier: a 128-bit value displayed as 32 hexadecimal digits in the pattern 8-4-4-4-12 (for example 3d7f2a9c-41b5-4e88-9f21-c58a0d92b7ef). Version bits inside declare how it was made; v4 means 'from random bits'.

**Can two UUID v4 values collide?**

In theory yes, in practice no. You'd need on the order of 2.7 quintillion v4 UUIDs before a duplicate becomes likelier than not; at a billion per second that is ~85 years of continuous generation for 50/50 odds. Within any realistic database the probability is negligible.

**What is the difference between a GUID and a UUID?**

None functionally. 'GUID' is Microsoft's name for the same 128-bit construct used in Windows/COM/SQL Server; 'UUID' comes from the ITU/ISO and IETF specs. Modern Microsoft docs use both interchangeably, and this generator's output is valid as either.

**Which UUID version should I use?**

Default to v4 when uniqueness alone matters and nothing should be inferable. Prefer v7 (or v6) for database primary keys where insertion-order sortability reduces index churn. Use v5 only when you need the same input to always yield the same ID.

**Are UUID v4 values cryptographically secure?**

They are unpredictable when built on a CSPRNG like crypto.getRandomValues(), as this tool does. Note the distinction: unpredictability makes them hard to guess, but they are identifiers, not authentication tokens — for secrets use a dedicated token generator.

**Are UUIDs safe in URLs and filenames?**

Yes. Hex digits plus hyphens need no percent-encoding, they never collide with reserved path segments, and their fixed length keeps logs column-aligned. Lowercase is canonical; uppercase parses identically but byte-compare after normalizing case.

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