UUID is a 128-bit Universally Unique Identifier formatted as 32 hex characters in 5 hyphen-separated groups, used as unique IDs in databases and distributed systems.

Free Tool

UUID Generator

Q: Are UUIDs truly unique?

In practice yes. UUID v4 has 2^122 possible values, making collision probability astronomically small even at massive scale.

Generate UUID v4 (random) instantly. Bulk generate up to 100 UUIDs — copy, download, done.

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How to Use the UUID Generator

Set the quantity (1–100 UUIDs per generation).
Click Generate — UUIDs appear instantly.
Click Copy All to copy all generated UUIDs to your clipboard, or click directly on the output area.
Click Download .txt to save the UUIDs as a text file.

All UUIDs are generated using UUID version 4 (random), which uses cryptographically random bits for uniqueness. The probability of generating two identical UUID v4 values is astronomically small — approximately 1 in 5.3 × 10³⁶.

Key Features

Bulk generation — generate up to 100 UUIDs in a single click.
Cryptographically random — uses the browser's crypto API for maximum randomness.
Download as .txt — export UUIDs for use in scripts or databases.
Click-to-copy — click the output area directly to copy all UUIDs.
Zero dependencies — pure JavaScript, no libraries, no data sent to servers.

Frequently Asked Questions

What is a UUID?

UUID stands for Universally Unique Identifier. It is a 128-bit label formatted as 32 hexadecimal characters in 5 groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx. UUIDs are designed to be unique across space and time without requiring a central registration authority. They are widely used as primary keys in databases, identifiers for distributed system resources, session tokens, and file names where uniqueness is required without coordination between systems.

What is UUID v4 and how is it different from other versions?

UUID v4 is randomly generated — 122 of its 128 bits are random, with the remaining 6 bits reserved for version and variant indicators. This makes it the simplest and most commonly used version for general-purpose unique identifiers. UUID v1 is time-based and includes the machine's MAC address, which raises privacy concerns. UUID v3 and v5 are namespace-based and deterministic (the same input always produces the same UUID). UUID v4 offers the best balance of simplicity, privacy, and uniqueness for most use cases.

Are UUIDs truly unique?

In practice, yes. UUID v4 has 122 random bits, giving it 2¹²² possible values — approximately 5.3 × 10³⁶. Even if you generated one billion UUIDs per second for a trillion years, the probability of a collision would still be negligibly small. For systems that need absolute collision-free guarantees (like distributed databases with billions of records), additional safeguards like database unique constraints are recommended alongside UUID generation.

Can I use these UUIDs as database primary keys?

Yes, UUID v4 values are widely used as database primary keys, especially in distributed systems where multiple servers need to generate IDs without coordination. The main trade-off versus auto-incrementing integers is that UUIDs are larger (36 characters versus a few digits), can fragment indexes in some database engines (particularly MySQL InnoDB), and are harder to read in logs. For PostgreSQL, using the uuid data type stores UUIDs efficiently as 16 bytes. For systems where sequential ordering matters, UUID v7 (time-ordered) is a better choice, though it is not yet universally supported.