UUID Generator (v4 and v7)

This UUID generator makes up to 1,000 UUIDs at once, either version 4 (fully random) or version 7 (time-ordered, from RFC 9562). You can switch to upper case, wrap each one in braces or drop the hyphens, then copy the list or download it as a text file. The values are made in your browser with crypto.getRandomValues, so nothing is sent to a server.

How to use the UUID generator

Pick the version, set how many you need and press Generate. Changing a format option regenerates the list. Download .txt saves one UUID per line, which is handy for seeding test data or bulk imports.

v4 or v7: which should you use?

A version 4 UUID is 122 random bits plus the version and variant bits. It reveals nothing about when or where it was made, which makes it a good default for public identifiers such as API keys for objects, upload names or session IDs that need to be hard to guess.

A version 7 UUID starts with a 48-bit Unix timestamp in milliseconds, followed by random bits. Because the timestamp comes first, new values sort after older ones. That keeps B-tree indexes in MySQL, MariaDB and PostgreSQL compact when the UUID is a primary key, because inserts land at the end of the index instead of at random pages. The trade-off is that anyone holding the UUID can read its creation time. This generator also keeps a small counter so that UUIDs made in the same millisecond still come out in order.

Formats

• Standard: 36 characters, lower case, as in 0192f0c4-7a1e-7c3b-9d2e-5b8f1a2c3d4e. RFC 9562 recommends lower case output and case-insensitive input.
• Upper case: some Windows tools and older .NET code print GUIDs this way.
• Braces: the registry and COM style, {...}.
• No hyphens: 32 hex characters, useful for file names or a BINARY(16) column loaded with UNHEX().

UUIDs on the command line

On a server you rarely need a website for this. These commands give a random (v4) UUID:

cat /proc/sys/kernel/random/uuid
uuidgen -r
python3 -c "import uuid; print(uuid.uuid4())"
# PowerShell
[guid]::NewGuid()

MariaDB 10.7 and later have a native UUID column type, and MySQL 8 has UUID_TO_BIN(uuid, 1) to store time-based UUIDs compactly. If you store UUIDs as text, use CHAR(36) with an ASCII character set rather than a multi-byte one, so the index stays small.

Are UUIDs unique and safe?

With 122 random bits, the chance of two v4 UUIDs colliding is so small that it can be ignored in practice, as long as the random source is good. This tool uses the browser’s cryptographically secure generator. Still, a UUID is an identifier, not a secret: do not use it as a password or as the only protection for a private link.

Related tools: Hash Generator (MD5, SHA-1, SHA-256, SHA-512) · Secure Password Generator · Unix Timestamp Converter · Number Base Converter.

Official documentation (checked 9 October 2026): RFC 9562: Universally Unique IDentifiers (UUIDs) · MDN: Crypto.getRandomValues()

Frequently asked questions