UUID Generator

How to Generate a UUID

1. Enter how many UUIDs you need (1–100).
2. Click Generate. Every UUID is produced in your browser using the Web Crypto API's crypto.randomUUID() — nothing is sent to a server.
3. Click Copy All to copy the list to your clipboard, or click individual UUIDs to copy a single value.

What Is a UUID?

A UUID (Universally Unique Identifier), also called a GUID in Microsoft contexts, is a 128-bit label used to identify records, sessions, and resources without a central authority. The canonical string form is 36 characters: xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx, where M encodes the UUID version (1, 4, 7, etc.) and N encodes the variant.

UUID Versions Compared

• UUID v1 — Built from a timestamp + MAC address. Predictable, leaks hardware info. Rarely used today.
• UUID v4 — Fully random (122 bits of entropy). The default for most modern apps. Generated by this tool.
• UUID v6 — Rearranged v1 that sorts chronologically. Good for databases but less common.
• UUID v7 — Time-ordered UUID with a millisecond timestamp prefix. Excellent for database primary keys because inserts stay sequential.

If you need sortable IDs for a B-tree index, consider ULID or UUID v7. If you just need "give me a unique value", v4 is the right choice.

UUID v4 in Code

In most modern stacks you don't need a library — the runtime has a built-in:

// JavaScript / TypeScript (browser & Node 19+)
const id = crypto.randomUUID();

// Python 3.x
import uuid
id = str(uuid.uuid4())

// Go
import "github.com/google/uuid"
id := uuid.NewString()

// Rust
use uuid::Uuid;
let id = Uuid::new_v4().to_string();

// PostgreSQL
SELECT gen_random_uuid();

// Swift
let id = UUID().uuidString

When to Use a UUID

• Distributed primary keys — when multiple services need to mint IDs without talking to a central database.
• Session and request IDs — trace a request across microservices without collisions.
• Idempotency keys — pass a UUID in API requests so retries don't double-charge a user.
• File and object names — using a UUID as the filename (e.g. 9f1c…d3a2.jpg) avoids naming conflicts in S3, R2, or disk storage.
• Invite tokens — v4's 122 bits of entropy make UUIDs unguessable enough for short-lived tokens.

Are UUIDs Really Unique?

UUID v4 has 122 random bits, so you would need to generate roughly 2.71 quintillion (2.71 × 10¹⁸) UUIDs before hitting a 50% chance of a single collision. At 1 billion UUIDs per second, that takes ~85 years. For every practical purpose, v4 UUIDs are unique.

Related Tools

Need unique IDs that are shorter or time-ordered? Generate strong random strings with the password generator, hash values with the hash generator, or encode binary data with the Base64 encoder.