UUID Generator - Bulk Random UUID/GUID
Generate UUID v1 / v3 / v4 / v5 in bulk
What Is a UUID?
A UUID (Universally Unique Identifier, also known as a GUID) is a 128-bit identifier with the format xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx (8-4-4-4-12), used to uniquely identify information in distributed systems. Because it can be generated locally without a central registry, UUIDs are widely used for database primary keys, distributed system IDs, API request tracing and session identifiers.
UUID Version Overview
v1 (Timestamp): generated from the current timestamp and a MAC address; it can be traced back to its generation time but may expose host information. v3 (MD5 Namespace): generated from an MD5 hash of a namespace and a name, so identical input always produces the same UUID. v4 (Random): generated purely from random values — the most commonly used version, recommended for most scenarios. v5 (SHA-1 Namespace): the same principle as v3 but it uses the more secure SHA-1 hash. v3/v5 require a namespace name and suit scenarios that need deterministic identifiers.
How to Use This Tool
Choose a UUID version (v4 by default), set how many to generate (1–100), and optionally enable uppercase output or remove hyphens. When you select v3 or v5 you must enter a namespace name. Click the "Generate" button to create them in bulk; each UUID has its own copy button, or you can copy all results at once. The generated UUIDs suit database primary keys, test identifiers and unique IDs in distributed systems. When you need to build sample data in bulk, pair this with the Random Data Generator.
UUID Generator FAQ
Can UUIDs repeat? How likely is a collision?
UUID v4 is generated purely from random values. Theoretically the 128-bit space has 2¹²⁸ possible values, so the collision probability is extremely low. Even generating 1 billion UUIDs per second, a collision would still only have an extremely small chance of occurring after about 85 years — in practice it can be considered effectively unique.
What is the difference between UUID v1, v4 and v5?
v1 is generated from a timestamp and a MAC address, carrying generation-time information but potentially exposing host info; v3 creates deterministic UUIDs from an MD5 hash plus a namespace, so the same input always yields the same UUID; v4 is fully random and the most commonly used version; v5 is similar to v3 but uses the more secure SHA-1 hash. For most scenarios, v4 is recommended.
What is the difference between UUID and GUID?
GUID (Globally Unique Identifier) is Microsoft’s name for UUID. Technically they are identical — both are 128-bit identifiers following the same format standard. The UUIDs generated by this tool can be used as GUIDs as well.
Is UUID a good choice for a database primary key?
The advantages of using a UUID as a primary key are global uniqueness, no need for central allocation, and easy merging across distributed systems. The downsides are larger storage (16 bytes vs 4 bytes for an auto-increment INT) and possible index page splits that may affect write performance. Choose based on the scenario: prefer UUIDs in distributed systems, and consider auto-increment IDs or ULID for single-machine high-write scenarios.
Is this UUID generator secure? Will my data leak?
It is safe. All UUID generation happens locally in your browser using the cryptographically secure random source crypto.getRandomValues, and no data is uploaded to any server. Formatting options such as removing hyphens or switching to uppercase are also handled entirely on the frontend.