Developer tool
UUID v4 Generator
Generate one or many random UUID v4 values. Copy the list or download it as a text file.
What is a UUID?
A UUID (universally unique identifier) is a 128-bit label written as 32 hexadecimal digits in five groups: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. Version 4 UUIDs are generated from random data, apart from six fixed bits that identify the version and variant.
They are useful when you need an identifier without asking a central database for the next number. A UUID v4 is not guaranteed to be unique, but the random space is large enough that accidental collisions are extremely unlikely for ordinary applications.
How this generator works
The page uses crypto.randomUUID() when your browser provides it. Otherwise it fills 16 bytes with crypto.getRandomValues() and sets the version and variant bits itself. All of that happens locally.
UUIDs are identifiers, not secrets
A UUID is designed to be shared. It is not a password, an access token or a security boundary. If a resource must be private, protect it with authentication and authorization. Do not rely on an unguessable URL alone.
When to use a UUID
- Database rows that may be created on different servers.
- Client-side objects that need an ID before they are saved.
- Idempotency keys and request IDs in logs.
- File names or temporary identifiers where a random label is convenient.
Versions and formatting
This tool generates version 4 UUIDs in the standard lowercase form. The uppercase option changes the presentation only; it is the same kind of identifier. UUIDs are case-insensitive when compared, but pick one style for consistency.
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Questions
Are these UUIDs random?
Yes. They are generated from the browser's cryptographic random source, not from a predictable counter.
Can two generated UUIDs be the same?
It is possible in theory because the space is finite, but the probability is negligible for normal use. A version 4 UUID has 122 random bits.
Are UUIDs safe to use as passwords?
No. UUIDs are identifiers and are often logged or shared. Use a password generator for passwords and a dedicated token system for access.
What does uppercase change?
Only the letters A–F are displayed in uppercase. The underlying value and randomness are the same.
Should I store a UUID as text or binary?
Either works. Text is easier to read and debug; binary is more compact. Pick one format and keep it consistent in your database.
Can I generate UUID v1 or v7 here?
No. This tool generates version 4 random UUIDs only. Use a library if you need time-based or sortable UUID versions.