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UUID / GUID Generator — Universal Unique ID

Generate cryptographically secure UUIDs / GUIDs (v4) instantly — universally unique identifiers in bulk, 4 formats, free.

✓ Free✓ No Login✓ UUID v4✓ Bulk Generate✓ 4 Formats✓ Download TXT

How Many UUIDs5

150

Format

1 UUID Generated

18bc8e090-b2a2-4d0f-933d-fe3a43f33fc1

📚 UUID Structure

550e8400-e29b-41d4-a716-446655440000

Time low (8 hex)

Time mid (4 hex)

Version + time (4 hex)

Variant + clock (4 hex)

Node / random (12 hex)

⚡ Common Uses

→Database primary keys

→Session & auth tokens

→API request IDs

→File & asset naming

→Distributed system IDs

→Transaction references

⚡

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UUID v1/v5, bulk export CSV, API access

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UUID Versions Explained

There are five UUID versions (v1–v5), each using a different algorithm. v4 is by far the most common for web and software applications.

VersionMethodRandom bitsSystem-safeBest for

UUID v1 Timestamp + MAC address0⚠ Leaks MACTime-series data, log ordering

UUID v4 RecommendedCryptographic random (CSPRNG)122✓ YesMost use cases — DB keys, tokens

UUID v5 SHA-1 hash of namespace+nameN/A✓ YesReproducible IDs from same input

📖 How to Use the UUID Generator

Set the Quantity

Use the slider to choose how many UUIDs to generate at once — from 1 to 50.

Choose a Format

Pick Standard, UPPERCASE, No Hyphens or With Braces depending on what your code or database requires.

Generate & Export

Click Generate. Copy individual UUIDs, Copy All as a newline-separated list, or Download TXT for database seeding scripts.

❓ Frequently Asked Questions

What is the difference between a UUID and a GUID?+

None in practice — GUID (Globally Unique Identifier) is Microsoft's name for the same 128-bit standard; UUID (Universally Unique Identifier) is the RFC 4122 term. Every UUID this tool generates is a valid GUID — use the braces output format for Microsoft-style {xxxxxxxx-...} values.

How many bytes is a UUID (and how long is it)?+

A UUID is 128 bits = 16 bytes of data, written as a 36-character string: 32 hexadecimal characters plus 4 hyphens. Version 4 contains 122 random bits, which allows about 5.3 x 10^36 possible values — enough that collisions are effectively impossible.

What is a UUID?+

A UUID (Universally Unique Identifier) is a 128-bit identifier formatted as 32 hexadecimal characters separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. It is designed to be unique across all space and time without a central authority.

What is the difference between UUID v1 and v4?+

UUID v1 is based on the current timestamp and the MAC address of the machine generating it. UUID v4 is randomly generated. v4 is recommended for most applications as it does not leak system information like MAC address or creation time.

Are UUIDs truly unique?+

UUID v4 uses 122 bits of randomness, giving 2^122 possible values (~5.3 × 10^36). The probability of generating two identical UUIDs is astronomically small — effectively zero for any practical use case.

What are UUIDs used for?+

UUIDs are used as primary keys in databases, session tokens, transaction IDs, file names, API request IDs, and anywhere a unique identifier is needed without coordination between systems.

Is it safe to use UUIDs as public-facing IDs?+

UUID v4 is safe to expose publicly as it reveals no information about your system. However, they are guessable in theory (given enough attempts), so for security-sensitive tokens consider using a cryptographic random string instead.

How RFC 4122 / RFC 9562 UUID v4 Identifiers Guarantee Global Uniqueness

A Universally Unique Identifier (UUID), standardized in RFC 4122 and updated in RFC 9562, is a 128-bit number formatted as 32 hexadecimal digits across five hyphen-separated groups (8-4-4-4-12, such as 550e8400-e29b-41d4-a716-446655440000). Unlike auto-incrementing SQL integers (1, 2, 3...) that leak total record counts to competitors and collide when merging distributed databases or generating offline client IDs, UUIDs can be generated independently on any client or microservice with zero central coordination.

In a Version 4 (random) UUID, 6 bits are reserved to denote the version (0100 for v4) and variant (10xx for RFC 4122), leaving 122 bits of pure cryptographic randomness—a total keyspace of 5.3 × 10^36 possible identifiers. To reach even a 50% probability of a single collision (the birthday paradox), you would have to generate 1 billion UUIDs every second for roughly 85 years.

PursTech's UUID Generator uses your browser's native W3C Web Crypto API (crypto.randomUUID() and crypto.getRandomValues()) to generate single or bulk UUIDs in standard, uppercase, compact (no hyphens), or SQL/JSON-wrapped formats.