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UUID v4 Generator

Generate cryptographically secure UUID v4 values in bulk. Copy them individually or all at once. Nothing leaves your browser.

How UUID Generator works

The UUID generator produces version 4 (random) UUIDs using the browser's built-in crypto.randomUUID() function, which draws from the operating system's cryptographically secure random number generator. You can generate version 4 (random) or version 7 (time-ordered) UUIDs, one at a time or in a batch of up to 100, then copy the list or download it as a text file. Because the entropy source is local hardware, nothing you generate ever touches a server.

UUID v4 consists of 122 random bits arranged in the standard 8-4-4-4-12 hex format (for example, 550e8400-e29b-41d4-a716-446655440000). The version nibble is fixed at 4 and the variant bits at 10xx, so every output is a valid RFC 4122 UUID. The browser's CSPRNG is the same source used for TLS key generation, which means collision probability across the full v4 space is negligible for any practical use.

Written by Bastien Sulyan

How to use UUID Generator, step by step

  1. Set the quantity of UUIDs you want to generate.
  2. Click "Generate" to produce the list.
  3. Click "Copy all" to copy every UUID to your clipboard.
  4. Optionally click "Download" to save the list as a plain-text file.

Common use cases

  • Generate a batch of primary keys for seeding a local development database before running migration scripts.
  • Produce a unique correlation ID to paste into a bug report so support can trace a specific request through distributed logs.
  • Create a set of test UUIDs for unit tests that assert your UUID validation logic rejects malformed inputs.
  • Generate a client-side idempotency key for an API request to avoid duplicate submissions on a flaky network.

Frequently asked questions

Are the generated UUIDs sent to a server for storage or logging?

No. The entire generation happens inside this browser tab using crypto.randomUUID(), a browser API that calls your OS CSPRNG locally. The output appears only in your browser; it is never transmitted to Sunasty or any third party.

How random are these UUIDs? Are they safe to use as primary keys?

UUID v4 contains 122 bits of entropy from a cryptographically secure source. The probability of two random v4 UUIDs colliding is approximately 1 in 5.3 * 10^36, which is negligible for any database size you are likely to encounter in practice.

Is crypto.randomUUID() available in all browsers?

Yes. It has been supported in Chrome since version 92, Firefox since 90, Safari since 15.4 and Edge since 92. All modern browsers released after mid-2021 support it. There is no fallback: on a browser without crypto.randomUUID(), version 4 generation fails rather than reaching for a weaker source of randomness. Version 7 is built from crypto.getRandomValues(), which has been available far longer.

Can I generate UUIDs in a specific version other than v4?

This tool generates version 4 (random) and version 7 (time-ordered, RFC 9562). Pick the version above the output. Version 1 (time-based with MAC address) is intentionally excluded because exposing your MAC address in a generated value is a privacy concern. Version 5 (namespace + SHA-1) requires a namespace input, which is a different workflow and not currently implemented here.

What is the maximum number of UUIDs I can generate at once?

The current limit is 100 per batch to keep the UI responsive. For larger volumes, download the file, then repeat the generation. Each batch is independent: there is no state carried between batches.

Can I use this tool offline?

Yes. crypto.randomUUID() makes no network calls. After this page loads, you can disconnect from the internet and keep generating UUIDs without interruption.