UUID Generator

UUID Generator — Free UUID v4 generator. Generate 1–100 UUIDs instantly using the Web Crypto API. Uppercase, lowercase, or no-hyphens format. One-click copy. No signup required.

Format:

—Generated

4Version

122Bits

lower.Format

Click Generate to create UUIDs

How to generate a UUID online

Choose how many — click 1, 5, 10, 25, or 50 to set the quantity.
Pick a format — lowercase (standard), UPPERCASE, or no-hyphens depending on your system's requirements.
Click Generate — UUIDs appear instantly.
Copy — click the copy icon next to any individual UUID, or use Copy All to grab the full list.

Every UUID is generated in your browser using the Web Crypto API. Nothing is sent to any server.

What is a UUID and what is it used for?

A UUID (Universally Unique Identifier) is a 128-bit value used to identify objects in computer systems without a central registration authority. The standard format is 32 hexadecimal digits grouped in five sections: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.

UUID v4 — the type this tool generates — is randomly created. With 122 bits of randomness, there are 5.3 × 10³⁶ possible values. The chance of two identical UUIDs being generated is negligible for any real-world use.

Common uses include database primary keys, session tokens, file names for uploaded assets, API resource identifiers, and distributed system IDs where multiple services need to create records without coordinating through a central counter.

UUID format options explained

Lowercase — 550e8400-e29b-41d4-a716-446655440000

The standard UUID format. Accepted by all databases, frameworks, and APIs. Use this unless you have a specific reason not to.

UPPERCASE — 550E8400-E29B-41D4-A716-446655440000

Functionally identical to lowercase. Sometimes used in legacy Windows systems, .NET GUIDs, and certain SQL Server contexts.

No hyphens — 550e8400e29b41d4a716446655440000

32 hex characters with no separators. Useful for filenames, URLs, and systems that reject hyphens in identifiers. Easily reversible — just insert hyphens at positions 8, 12, 16, and 20.

UUID v4 vs other UUID versions

Version	Based on	Best for
v1	Timestamp + MAC address	Time-ordered logs, leaks machine info
v3	MD5 hash of name	Deterministic IDs from known inputs
v4	Random	General purpose — most widely used
v5	SHA-1 hash of name	Deterministic IDs, more secure than v3
v7	Unix timestamp + random	Time-sortable IDs for databases (newer)

For most applications, UUID v4 is the right choice. If you need sortable IDs for high-write database workloads, look into UUID v7 or ULID. For a secure random password, use the dedicated password generator instead.

Frequently Asked Questions

What is a UUID?

UUID stands for Universally Unique Identifier. It is a 128-bit label used to uniquely identify information in computer systems. A UUID v4 is randomly generated, making the probability of two identical UUIDs astronomically small.

What is UUID v4?

UUID v4 is the most widely used UUID variant. It is generated from random numbers, unlike v1 (timestamp-based) or v5 (name-based hashing). The format is xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx where x is random and y is one of 8, 9, a, or b.

Are these UUIDs truly unique?

Yes, for all practical purposes. UUID v4 has 122 bits of randomness, giving 5.3 × 10³⁶ possible values. The probability of generating two identical UUIDs is negligibly small — roughly 1 in a billion if you generated a billion UUIDs per second for a hundred years.

Is it safe to use these UUIDs in production?

Yes. This tool uses crypto.randomUUID() (where available) or crypto.getRandomValues() as a fallback — the same Web Crypto API used for browser encryption. UUIDs are generated entirely in your browser and never sent to any server.

What format should I use?

Lowercase with hyphens is the standard UUID format and is accepted by all databases and systems. Uppercase is sometimes used for display purposes. No-hyphens is useful when embedding a UUID in a filename, URL, or system that does not allow special characters.

Can I use these UUIDs as database primary keys?

Yes. UUID v4 is a common choice for distributed systems where you need globally unique IDs without a central coordinator. Note that random UUIDs can cause index fragmentation in some databases — for high-write workloads, consider UUID v7 (time-ordered) instead.