UUID / GUID Generator — Free Bulk Generator, No Signup
Generate one or a thousand random UUIDs in seconds — v4 (random) or v1 (timestamp). Copy them all with one click.
Generation Settings
Generate a UUID online — how it works
Pick how many you need (1 to 1000), choose the version, and hit Generate. The UUIDs appear in the box immediately — click Copy All to grab them. UUID v4 is the right choice for almost everything. It's purely random with no information about your machine or the time baked in. UUID v1 includes a timestamp, which makes IDs sortable by creation time but historically leaked MAC address info (this tool randomizes the node component).
UUID vs GUID — is there a difference?
No meaningful difference. GUID (Globally Unique Identifier) is just what Microsoft called UUIDs. They follow the same RFC 4122 standard, have the same 128-bit format, and are interchangeable. If a Windows API asks for a GUID, give it a UUID — same thing.
UUID v4 vs v1 vs v7 — which one should you use?
| Version | How it's made | Use when |
|---|---|---|
| v4 (random) | 122 bits of random data | Default choice — database IDs, session tokens, anything where order doesn't matter |
| v1 (timestamp) | Timestamp + node identifier | When you need IDs to be sortable by creation time (older, has privacy caveats) |
| v7 (time-ordered) | Millisecond timestamp prefix + random | Modern replacement for v1 — sortable and random, no privacy issues. New projects should prefer this. |
Why UUIDs beat auto-increment integers for most cases
- No central coordinator needed — any service can generate IDs independently without talking to a database first
- Don't reveal record counts — sequential IDs expose how many users/orders you have. UUIDs don't.
- Safe to merge databases — merge two databases with UUID primary keys and there are no conflicts
- Generate IDs on the client — create the ID before hitting the API, which simplifies optimistic UI updates
The tradeoff is index performance. UUID v4 primary keys cause more index fragmentation in B-tree indexes than sequential integers. For high-write databases this matters — consider UUID v7 (time-ordered) or a ULID if you need both uniqueness and decent index locality.
Complete Developer Toolkit
UUIDs are used as primary keys, session identifiers, request trace IDs, and file names throughout modern applications. Once you've generated your UUIDs, use our JSON formatter to embed them cleanly in JSON config files or API payloads. Our JWT decoder is closely related — JWTs often contain a jti (JWT ID) claim which is a UUID used to prevent token replay attacks. When storing UUIDs in databases, our SQL formatter helps you write the INSERT or UPDATE queries cleanly.
For encoding UUIDs in URL-safe or binary contexts, our Base64 encoder converts UUID bytes to a compact string, and our URL encoder ensures UUID strings are safe in query parameters. Our regex tester helps you write validation patterns for UUID format checking — the standard pattern is [0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}. For checking DNS records associated with services using UUIDs as resource identifiers, our DNS lookup tool queries live DNS records. The API response simulator generates mock JSON responses that include UUID fields for testing your client-side UUID handling.