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Free Online UUID Generator (v1, v4, v5, NIL)
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This UUID generator creates RFC 4122 compliant universally unique identifiers in your browser, supporting random v4 UUIDs, timestamp-based v1 UUIDs, name-based v5 UUIDs, and the special all-zero NIL UUID. UUIDs are the backbone of distributed systems — database primary keys, API resource IDs, session tokens, and distributed tracing all rely on the near-certainty that two independently generated UUIDs will never collide, which is exactly what version 4's 122 bits of randomness guarantees for practical purposes. Backend developers seeding test data, database architects choosing primary key strategies, and anyone needing a quick batch of unique identifiers will find this generator fast and reliable. Every UUID is generated locally using your browser's cryptographically secure random number generator via JavaScript — nothing is transmitted to or logged by a server, and batch generation lets you create hundreds at once for seed scripts or fixtures. There's no signup and no limits. If you need to validate an existing UUID's version and format instead, this platform also has a dedicated UUID validator. Scroll down to generate your UUIDs now.
Features
- Generates UUID v4 (random) using cryptographically secure randomness
- Generates UUID v1 (timestamp + node-based)
- Generates UUID v5 (name-based, SHA-1 namespace hashing)
- Supports the special all-zero NIL UUID
- Batch generation of multiple UUIDs at once
- Standard RFC 4122 hyphenated format output
- One-click copy to clipboard for single or bulk results
- Fully client-side, no server round trip
Why use this uuid generator (v1, v4, v5, nil)?
- Instant generation, even in bulk batches
- Fully private — UUIDs are generated entirely in your browser
- RFC 4122 compliant output guaranteed to match standard libraries
- Flexible support for multiple UUID versions in one tool
- Free with unlimited generation and no signup
Frequently asked questions
What's the difference between UUID v1 and v4?
UUID v1 is generated from a timestamp and a node identifier (often derived from a MAC address), making it sortable by creation time but potentially revealing information; UUID v4 is purely random, offering better privacy and simplicity for most applications.
How unlikely is a UUID v4 collision?
With 122 random bits, you'd need to generate roughly 2.7 quintillion UUID v4s before there's even a 50% chance of a single collision, making it effectively negligible for real-world use.
What is a UUID v5 used for?
UUID v5 deterministically generates the same UUID from a given namespace and name using SHA-1 hashing, useful when you need a reproducible, unique ID from existing data rather than a random one.
What is the NIL UUID?
The NIL UUID is the special all-zeros value (00000000-0000-0000-0000-000000000000), used to represent an explicitly empty or unset UUID field.
Is UUID the same as GUID?
They're functionally the same concept — GUID (Globally Unique Identifier) is Microsoft's terminology for what the RFC 4122 standard calls a UUID.
Are UUIDs good database primary keys?
They work well for distributed systems avoiding key collisions across servers, though UUID v4's randomness can hurt index locality compared to sequential IDs — UUID v7 (time-ordered) is increasingly preferred for that reason.
Can I predict a UUID v4 before it's generated?
No, a properly generated UUID v4 relies on a cryptographically secure random source, making it computationally infeasible to predict.