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UUID v4 Generator

Generate one or up to 1,000 RFC 4122 version 4 UUIDs in one click. Uses crypto.randomUUID when available (or crypto.getRandomValues as a fallback), so the IDs are cryptographically random. Optional uppercase output and hyphen-free format. Combine it with the SHA Hash Generator when you want a deterministic ID instead of a random one, or with the Strong Password Generator when you actually need a secret.

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How it works

Each UUID is generated by crypto.randomUUID(), which under the hood pulls 16 random bytes from the OS CSPRNG, sets the version (0x40) and variant (0x80) bits and formats as 8-4-4-4-12 hex. Falls back to crypto.getRandomValues for older browsers.

How to use it

  1. Set the count

    Pick how many UUIDs to generate, from 1 to 1,000. One for an ad-hoc test, 100 for a database seed, more for a bulk migration.

  2. Toggle uppercase and hyphens

    Uppercase emits A-F instead of a-f. Hyphen-free strips the 8-4-4-4-12 dashes. Mix to match what your downstream system wants.

  3. Generate via Web Crypto

    crypto.randomUUID() pulls 16 bytes from the OS CSPRNG, sets RFC 4122 v4 bits and formats. Falls back to crypto.getRandomValues.

  4. Copy or download

    Take the UUID list into your DB seed, your test fixture, your filename batch, or your API mock. Each ID is unique enough to never collide.

Use cases

Seed primary keys for a new database table.

Generate request IDs for testing.

Mock up API responses with realistic IDs.

Create unique filenames before upload.

Pre-build IDs for a batch import script.

When NOT to use it

  • As a security token visible to clients. UUIDs are predictable enough to brute-force; use a 32-byte cryptographic random instead.
  • When you need sortable IDs. UUID v4 is fully random, so a sorted index gets random writes. Use UUIDv7, ULID or KSUID for time-ordered IDs.
  • When the IDs go in URLs and short is important. UUIDs are 36 chars (or 32 without hyphens). Shorter IDs like nanoid are friendlier to QR codes and sharing.

Your data never leaves your browser

Every utility runs entirely on your device. Nothing is uploaded, nothing is stored on a server. You can disconnect from the internet and they keep working.

Frequently asked questions

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