UUID generator

How to use the UUID generator

  1. Pick a UUID version: v4 (random, default — best for most use cases), v1 (timestamp-based), v7 (timestamp-prefixed, sortable — new as of 2024), or v5 (namespace-deterministic).
  2. Set quantity: generate 1 for a single ID, or up to 10,000 in bulk for seed data.
  3. Choose formatting: standard hyphenated, uppercase, compact (no hyphens), or Base64.
  4. Copy the list or download as a .txt file.

When to use it

Pick v4 when you just need unique IDs and sort order doesn't matter — 99% of cases. Pick v7 when IDs will be database primary keys and you want insertions to be roughly chronological (better B-tree index performance). Pick v1 only for legacy compatibility; v1 leaks the generating machine's MAC address in some implementations.

Frequently asked questions

Are these UUIDs cryptographically random?
v4 uses the browser's crypto.getRandomValues() — cryptographically strong on modern browsers.
Will two systems ever generate the same v4 UUID?
Statistically, no — the collision probability for 103 trillion v4s is 1 in a billion.
Why is v7 better for database keys?
v7 embeds a millisecond timestamp in the first 48 bits, so IDs insert in near-monotonic order. B-tree indexes handle monotonic inserts faster than random ones.
Can I generate UUIDs for a specific namespace?
Yes — v5 takes a namespace UUID and a name string and deterministically generates a UUID. Same inputs always produce the same output.

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Last updated: 2026-04-22