UUID v4 Generator
Generate cryptographically random UUID v4 identifiers. Bulk generate up to 100 at once, copy all, or download as a text file.
How to Use
Set the Quantity
Enter how many UUIDs you need in the quantity field — between 1 and 100. You can generate a single UUID for immediate use or a batch of up to 100 for seeding a database or test fixture.
Choose Format Options
Enable "Uppercase" to get UUIDs in capital letters (e.g., 550E8400-E29B-41D4...). Disable "Include hyphens" to get a compact 32-character hex string without separators — useful for some database systems.
Generate UUIDs
Click "Generate UUIDs" to instantly create the requested number of version 4 UUIDs using your browser's cryptographically secure random number generator. Each UUID in the list has its own "Copy" button.
Copy or Download
Click "Copy All" to copy every UUID to your clipboard (one per line), or click "Download .txt" to save the entire list as a plain text file. Individual UUIDs can also be copied using the button on each row.
Frequently Asked Questions
A UUID (Universally Unique Identifier), also known as a GUID (Globally Unique Identifier), is a 128-bit label used to uniquely identify objects in computer systems. Defined by RFC 4122, UUIDs are designed to be unique across time and space without requiring a central registration authority. They are represented as 32 hexadecimal digits displayed in five groups separated by hyphens: xxxxxxxx-xxxx-xxxx-xxxx-xxxxxxxxxxxx.
UUID version 4 (v4) is generated from random or pseudo-random numbers. It has 122 bits of randomness, with the remaining bits used for version and variant identifiers. The version is indicated by the character "4" in the third group, and the variant bits ensure compatibility. UUID v4 is the most commonly used version for generating unique IDs in applications because it requires no coordination with other systems.
Technically no — but the probability of a collision is astronomically low. With 122 bits of randomness in UUID v4, you would need to generate approximately 2.7 × 10¹⁸ UUIDs before a 50% chance of collision occurs. In practice, UUIDs are treated as unique for all real-world applications. This tool uses crypto.getRandomValues() for maximum randomness quality.
Yes, and it is a common practice. UUIDs as primary keys offer advantages: they can be generated on the client or application layer without a database round-trip, they work well in distributed systems, and they do not reveal record count or insertion order. The main trade-off is that UUIDs (16 bytes) are larger than integer keys (4–8 bytes) and can slightly reduce index performance in large tables. Some databases support a native UUID type for efficient storage.
A UUID is 128 bits (16 bytes) displayed as 32 hexadecimal digits in five groups separated by hyphens: 8-4-4-4-12 characters, e.g., 550e8400-e29b-41d4-a716-446655440000. The third group's first character indicates the version (4 for UUID v4). The fourth group's first character is either 8, 9, a, or b and indicates the RFC 4122 variant. The total string length is 36 characters including hyphens.