What is the difference between UUID v1, v4, and v7?

v1 embeds a MAC-derived node and a timestamp. v4 is fully random (no ordering). v7 combines a Unix timestamp with random bits so IDs sort roughly by creation time.

When should I use v7 instead of v4?

Choose v7 when you need time-ordered identifiers for databases or logs without a separate created_at index. v4 remains ideal when sort order must reveal nothing about timing.

Are these UUIDs cryptographically secure?

v4 and v7 random portions use secure randomness in the browser. v1 includes timing and may be more predictable; avoid v1 for security-sensitive tokens.

Can I generate many UUIDs at once?

Yes. Set the count and version, then copy the list or export as CSV for seed data, migrations, or bulk imports.

Do UUIDs ever collide?

Practically never for v4 and v7 at normal volumes. Collisions are astronomically unlikely; use ULIDs if you need shorter URL-safe strings with similar properties.

Is this the same format databases expect?

Output follows RFC 4122 canonical string form (8-4-4-4-12 hex). Paste into PostgreSQL, MySQL, or MongoDB UUID fields without transformation.

Are identifiers sent to a server?

No. Generation runs entirely in your browser; values are not uploaded or logged.

Can I use UUIDs as public IDs in URLs?

Yes, but prefer opaque random IDs (v4) over v1 if you want to avoid leaking hardware or timing hints.

UUID Generator

Generate Live

Generate v1, v4 and v7 UUIDs in bulk.

About this tool

UUID Generator — Generate v1, v4 and v7 UUIDs in bulk. Free, fast and private. Runs entirely in your browser at Quick Calci Tools.

Examples

Common scenarios for the UUID Generator.

Single v4

3b1f4ac6-ec27-4b8b-9f5a-9b34a7c0a1d2

Bulk v7 (10 sortable)

count: 10
version: v7

10 monotonically-increasing UUIDs.

Who uses the UUID Generator?

Common scenarios and audiences for this tool.

Backend engineers

Mint primary keys for new tables, microservices, or event payloads without a central ID service during development.

QA & test automation

Fill databases and API fixtures with unique IDs so parallel test runs never clash.

Data engineers

Add surrogate keys when staging files before loading into a warehouse or lake.

Mobile app developers

Generate offline-first client IDs that sync safely without collision when the device reconnects.

Technical writers

Drop realistic identifiers into docs and screenshots without exposing production data.

Frequently asked questions

Everything you need to know about the UUID Generator.