UUID Generator (v4, v7, v1)
Generate UUIDs in v4 (random), v7 (time-ordered), and v1 (time-based) formats — bulk-generate up to 1,000 at once, all in your browser.
Generated locally with the Web Crypto API. v1 here is a privacy-safe time+random variant (no MAC address).
About this tool
A UUID (universally unique identifier) is a 128-bit value used to label data without a central authority. This generator produces them in three versions. Version 4 is purely random — the most common choice for general IDs. Version 7 is time-ordered: it embeds a Unix millisecond timestamp in the high bits, so v7 UUIDs sort chronologically, which makes them excellent database primary keys (better index locality than v4). The v1-style option here is time-based but uses a random node instead of a hardware MAC address, avoiding the privacy leak of classic v1. Everything is generated locally with the Web Crypto API, so the values never leave your device, and you can bulk-generate up to a thousand at once and copy them all.
How to use it
- Choose the UUID version (v4, v7, or v1).
- Set how many to generate.
- Click Generate and copy the results.
- Use v7 when you want time-sortable IDs for databases.
Frequently asked questions
- What is the difference between UUID v4 and v7?
- v4 is entirely random, so the IDs are unpredictable but unordered. v7 embeds a Unix-millisecond timestamp in its leading bits, so v7 UUIDs are time-ordered and sort chronologically — which gives much better database index performance than scattered v4 values.
- Which UUID version should I use?
- Use v4 for general-purpose unique IDs where ordering does not matter. Use v7 for database primary keys or anything you want naturally time-sorted. Avoid classic v1 in public contexts because it can embed the machine’s MAC address.
- Are these UUIDs cryptographically random?
- Yes — they use the Web Crypto API (crypto.getRandomValues / crypto.randomUUID), which is seeded from the operating system’s entropy. The random portions are suitable for unguessable identifiers.
- Is the v1 here a real version 1 UUID?
- It is a privacy-safe variant: time-based like v1 but with a random node field instead of a hardware MAC address. True v1 embeds the MAC, which can leak device identity, so this tool avoids it deliberately.
- Are the UUIDs sent to a server?
- No. All generation happens locally in your browser. Nothing is transmitted or logged, so the identifiers stay private to your session.
- How unique are UUIDs?
- Extremely. A v4 UUID has 122 random bits, so collisions are astronomically unlikely even across billions of IDs. v7 adds a timestamp, further reducing collision risk while keeping the values ordered.