UUID Generator

UUID v4を生成。

CountUppercase

e959d885-16ec-4887-b848-7588f5e2fa1c

UUID v4

Cryptographically random via crypto.randomUUID().

Bulk Generate

Generate up to 100 UUIDs at once.

Copy Result

One-click copy to clipboard.

Client-side

All processing in your browser. No data uploaded.

UUID Generatorについて

A UUID (Universally Unique Identifier) is a 128-bit label used to uniquely identify objects in computer systems. Version 4 UUIDs are generated using cryptographically random numbers, making them statistically unique without any central coordination. They are formatted as 32 hexadecimal digits displayed in five groups separated by hyphens: xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. UUIDs are widely used in distributed systems, databases, and APIs as primary keys, session tokens, and request correlation IDs — anywhere you need a globally unique value that can be generated independently on any machine without risk of collision. This tool generates one or up to 100 UUIDs at once using the browser's built-in crypto.randomUUID() API, which guarantees cryptographic-quality randomness. You can toggle uppercase output and copy individual UUIDs or the entire batch with a single click. All generation happens entirely in your browser — nothing is sent to any server, so your identifiers remain private.

UUID Generatorの使い方

Choose how many UUIDs to generate (1–100) using the Count input.
Optionally check the Uppercase toggle if you need capital letters in the output.
Click Generate to create a fresh batch of cryptographically random UUID v4s.
Click Copy next to any individual UUID to copy just that one to your clipboard.
Click Copy All to copy the entire batch as newline-separated values.
Paste the UUIDs into your database, code, or configuration as needed.

よくある質問

Is UUID v4 truly unique?

UUID v4 uses 122 bits of randomness. The probability of generating a duplicate is so small (about 1 in 5.3×10³⁶) that for all practical purposes they are guaranteed unique, even if you generate billions of them.

What is the difference between UUID v1 and v4?

UUID v1 is based on the current timestamp and your machine's MAC address, which can leak information and may have collisions if generated quickly. UUID v4 is purely random, making it safer for most applications.

Can I use UUIDs as database primary keys?

Yes. UUIDs make excellent primary keys in distributed systems because they can be generated client-side without a round-trip to the database. The trade-off is that they are larger than integer keys and slightly slower to index.

Does this tool store the UUIDs it generates?

No. All generation happens locally in your browser using the Web Crypto API. No UUIDs or any other data are sent to our servers.

What format does UUID v4 use?

UUID v4 follows the RFC 4122 format: 8-4-4-4-12 hexadecimal characters separated by hyphens, totalling 36 characters including hyphens (32 hex digits).