Free UUID generator — UUID v4, ULID & NanoID online
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About Free UUID generator — UUID v4, ULID & NanoID online
UUID / ULID / NanoID Generator produces cryptographically secure random identifiers directly in your browser using the Web Crypto API. Choose the format, generate up to 1,000 at a time, and copy individually or in bulk. No IDs are ever transmitted.
Key Features
- UUID v4 generation with Web Crypto randomUUID where available
- ULID generation (timestamp-prefixed, lexicographically sortable)
- NanoID with configurable length from 4 to 64 characters
- Bulk generation up to 1,000 IDs per click
- Copy one or all IDs with a single click
- Pure browser JavaScript — no network, no tracking
Use Cases
- Generate database primary keys that are safe to expose
- Create idempotency keys for API requests
- Seed test fixtures, mock data, or QA environments
- Produce short, URL-friendly share links with NanoID
- Use ULIDs when you need time-ordered IDs in distributed systems
Pro Tips
- UUID v4 has ~122 bits of entropy — enough for nearly all apps.
- ULIDs sort lexicographically by creation time, making them ideal for log keys.
- NanoID of length 21 has entropy comparable to UUID v4 but is URL-safer.
- Always generate IDs on the client or server you trust — never from a public API you do not control.
- Store IDs as binary or native UUID types in Postgres / MySQL for best index performance.
Frequently Asked Questions
Are these IDs cryptographically secure?
Yes. All random bytes come from window.crypto.getRandomValues or crypto.randomUUID, which browsers back with a CSPRNG.
What is the difference between UUID v4 and ULID?
UUID v4 is fully random (no time component). ULID embeds a 48-bit millisecond timestamp followed by 80 bits of randomness, which means ULIDs generated close together sort naturally by time.
Why pick NanoID over UUID?
NanoID is shorter (21 chars vs 36), URL-safe, and allows you to trade length for entropy. It is popular for URL slugs, short IDs, and keys visible to end users.
Can I generate millions of IDs safely with this tool?
The UI caps bulk generation at 1,000 per click to keep the browser responsive. For very large batches, use a server-side library; the math for collisions favours UUID/NanoID well into the trillions with standard sizes.