~/tools/uuid-generator

UUID Generator

Generate UUID v4, v1, and v7 identifiers instantly — bulk generation, format options. Runs entirely in your browser, zero server calls.

// How to use

1. Select version (v4, v1, or v7)
2. Choose how many to generate
3. Set format and hyphen options
4. Click Generate
5. Copy individually or use Copy All
* all generation happens in browser

100% client-side — no data leaves your browser

uuid — generator

// Version

// Count

// Format

// Hyphens

// Press Generate to create UUIDs

What is a UUID?

A UUID (Universally Unique Identifier) is a 128-bit identifier standardised in RFC 4122. It is designed to be unique across all space and time without requiring a central registration authority. In its canonical form, a UUID is represented as 32 hexadecimal digits separated by hyphens into five groups: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.

UUIDs are also commonly referred to as GUIDs (Globally Unique Identifiers), a term popularised by Microsoft. Despite the different name, a GUID and a UUID are the same thing — the terms are interchangeable in modern usage.

UUID Versions

The UUID specification defines several versions, each with a different generation strategy. The version number is encoded in the UUID itself (the first digit of the third group), so you can always identify how a UUID was generated just by looking at it. For most new applications, v4 is the right choice — it requires no configuration and produces statistically unique identifiers with negligible collision probability.

v1

Time-based

Generated from the current timestamp and the MAC address of the machine. Monotonically increasing, which makes it sortable by creation time. The node portion is randomised in this tool since MAC addresses are not accessible in browsers.

v2

DCE Security

A variant of v1 that embeds POSIX UID/GID into the UUID. Rarely used outside of DCE/RPC systems. Not widely supported by UUID libraries.

v3

Name-based (MD5)

Deterministic — generates the same UUID for the same namespace and name every time, using MD5 hashing. Useful when you need consistent identifiers for well-known inputs.

v4

Random

122 bits of cryptographic randomness. No input required. The overwhelming choice for generating unique identifiers in web applications, databases, and distributed systems.

v5

Name-based (SHA-1)

Like v3 but uses SHA-1 instead of MD5. Preferred over v3 when deterministic UUIDs are needed, due to SHA-1's better collision resistance.

v7

Unix-time ordered

Introduced in RFC 9562 (2024). Combines a millisecond-precision Unix timestamp prefix with random bits. Naturally sortable by creation time — ideal for use as database primary keys.

UUID v4 Structure

A v4 UUID looks random, but its structure encodes two fixed pieces of metadata that identify it as a valid UUID. These bits are set deterministically regardless of the random content around them, which means you can verify a v4 UUID just by inspecting two character positions in the string.

// Example v4 UUID — annotated

550e8400-e29b-41d4-a716-446655440000

4Version bit — always "4" for UUID v4

8, 9, a, bVariant bits — first char of 4th group is always one of these

Common Use Cases

UUIDs are used wherever a system needs to assign a unique identifier without coordinating with a central authority. This makes them especially valuable in distributed systems, offline applications, and microservice architectures where sequential integer IDs would require a shared database sequence or a central ID-generation service.

Database Primary Keys

Assign IDs to records without a database round-trip. Especially useful in insert-heavy or offline-first applications.

API Resources

Expose resource identifiers in REST or GraphQL APIs that don't leak enumeration information the way sequential integers do.

Session & Token IDs

Generate unguessable session tokens, CSRF tokens, or one-time links for password resets and email verification.

File & Asset Names

Rename uploaded files to avoid collisions and prevent users from guessing other files' URLs.

Distributed Tracing

Tag requests with a trace ID as they move across microservices so logs from multiple systems can be correlated.

Idempotency Keys

Send a UUID with payment or mutation requests so the server can safely retry without causing duplicate operations.