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UUID Generator

Generate RFC 4122 version 4 UUIDs in your browser, up to 100 at a time, and validate any UUID you already have — format, version and variant.

Generate UUIDs

Version 4 (random), from crypto.randomUUID(). No UUID is sent anywhere — this page has no server to send it to.

Inspect a UUID

Paste any UUID — the inspector reports the format, the version nibble and the variant bits.

The inspector reports only what the bits show. A “v1” UUID claims a timestamp and node ID — this tool does not check either.

Your file is never sent to a server. It is read and processed by your own browser, and the results are not stored.

How to use it

  1. Choose how many UUIDs to generate (1–100) and generate.
  2. Copy the list, or download it as a .txt file.
  3. To validate, paste a UUID into the inspection box and read the verdict.

Limits worth knowing

  • Generation is v4 only; the inspector reports v1/v3/v4/v5/v6/v7/v8, nil and max honestly.
  • No database round-trip and no duplicate check against your systems.
  • Duplicates in a list are exceedingly unlikely — generation uses a fresh CSPRNG draw per UUID.
  • Generation is capped at 100 per batch.

What v4 actually guarantees

A v4 UUID is 122 random bits with the version and variant nibbles fixed. Nothing about it encodes the time or machine, which is why it is safe to expose in URLs and logs. It also buys you nothing about uniqueness beyond the probability that the space collides — about one in 5.3 × 10^36 for two UUIDs.

Use v7 (time-sortable) if your storage engine cares about index locality; this tool does not generate it, and that is deliberate rather than an oversight.

Reading the inspector verdict

The inspector reports the hex shape, the version nibble in the third group, and the variant bits in the fourth. A “v1” UUID claims a timestamp and node ID; it may or may not be correctly shaped beyond that, and the tool says only what the bits show.

Frequently asked questions

Does UUID Generator upload my files to any server?

No. UUID Generator runs in your browser, and the file is read there rather than sent to a server for processing. Our host still sees ordinary page-request metadata, which is described on the privacy page.

Is UUID Generator free to use?

Yes, UUID Generator is free, with no paid tier, no account, and no watermark added to your output. The limits are technical rather than commercial: file size, page count and supported formats are listed on this page.

What file formats and sizes are supported?

UUID Generator supports .txt files up to 1MB directly in your browser.

Are these UUIDs safe for database keys?

Yes for v4’s intended use: 122 random bits per UUID, generated by your browser’s cryptographic random source. They are not sequential, so do not use them where sort order matters.

Where does the randomness come from?

crypto.randomUUID() when available, with a crypto.getRandomValues() fallback that writes the version and variant bits itself. Both use your browser’s CSPRNG.

Can it generate v1 or v7 UUIDs?

No. It generates and validates v4 — the one everyone actually wants. Validating other versions reports which version the bits claim, including nil, max and odd ones.

Is anything uploaded?

No. No UUID is sent anywhere; the validator inspects the string you paste.