UUID Generator
Generate universally unique identifiers (UUIDs) for databases, distributed systems, and testing.
Generated UUIDs
Total UUIDs
0
Version
4
Format
xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx
What is a UUID?
128‑bit unique identifier
A Universally Unique Identifier (UUID) is a 128‑bit number used to uniquely identify information in computer systems. The standard representation uses 36 characters: 32 hexadecimal digits separated by four hyphens (e.g., 123e4567-e89b-12d3-a456-426614174000).
Why use a UUID? They are ideal for distributed systems, database keys, and scenarios where you need identifiers that are unique across space and time without central coordination.
This generator supports:
- Version 4 (Random): 122 random bits. Fast and suitable for most applications.
- Version 1 (Time‑based): Uses timestamp and node (MAC address). Can be predictable but includes time ordering.
- Version 5 (Name‑based): Generated from a namespace and name using SHA‑1. Always produces the same UUID for same inputs.
People Also Ask
🔢 What's the difference between UUID v1 and v4?
v1 uses timestamp + MAC address, so it's sortable but exposes the machine's MAC. v4 is completely random, offering more privacy but no inherent order.
📅 Can UUIDs ever repeat?
Probability of collision is extremely low (for v4, ~1 in 5.3×10²⁰). For practical purposes, they are unique.
🌐 What is a namespace UUID in v5?
A predefined UUID (like DNS: 6ba7b810-9dad-11d1-80b4-00c04fd430c8) that scopes the name to avoid collisions across different domains.
💾 How many UUIDs can I generate?
This tool allows up to 100 at once. For bulk generation, run multiple times.
UUID Versions Explained
| Version | Method | Use Cases |
|---|---|---|
| v1 (Time-based) | 60‑bit timestamp + clock sequence + MAC address | When sortability and traceability matter (e.g., distributed logs). |
| v4 (Random) | 122 random bits (6 bits reserved for version/variant) | General‑purpose, databases, primary keys. |
| v5 (Name-based) | SHA‑1 hash of namespace + name | Generating consistent UUID from a known string (e.g., URL, domain). |
This implementation follows RFC 4122. All generated UUIDs include the correct version and variant bits.
Frequently Asked Questions
How are UUID v4 generated?
We use the browser's
crypto.randomUUID() when available (modern browsers). Otherwise, we fallback to a high‑quality random number generator (crypto.getRandomValues). The version nibble (4) and variant bits are set according to RFC.What about UUID v1 and the node (MAC address)?
Our v1 implementation uses a random 48‑bit node identifier (not your actual MAC) for privacy. The timestamp is based on system time and a simulated 100ns counter. This still yields unique, time‑ordered UUIDs.
Why do v5 UUIDs require a namespace?
The namespace ensures that the same name in different contexts produces different UUIDs. Standard namespaces exist for DNS, URL, OID, and X.500. We pre‑fill with the DNS namespace if you leave it blank.