UUID v4 is a randomly generated universally unique identifier in the format xxxxxxxx-xxxx-4xxx-yxxx-xxxxxxxxxxxx. The "4" indicates version 4, and the high bits of the third group indicate the variant. It has 122 bits of randomness.

How random are these UUIDs?

They use crypto.randomUUID() which is backed by the operating system's cryptographically secure random number generator (CSPRNG) — the same source used for cryptographic keys.

What is the difference between a UUID and a GUID?

Functionally the same. GUID (Globally Unique Identifier) is Microsoft's term for UUID. Both follow the same RFC 4122 standard.

Can I generate UUIDs without hyphens?

Yes. Toggle the "Remove hyphens" option to generate compact 32-character hex strings without the standard hyphen separators.

What is the difference between UUID v1, v4, and v7?

UUID v1 is time-based and includes the MAC address — predictable and has privacy implications. UUID v4 is randomly generated. UUID v7 (2024 standard) encodes a Unix millisecond timestamp in the first 48 bits for natural time-sortable ordering in databases.

Should I use UUID or ULID for database primary keys?

ULID (Universally Unique Lexicographically Sortable Identifier) is better for database primary keys because it is time-sorted, which improves B-tree index performance. UUID v7 achieves the same goal within the UUID standard. UUID v4 random inserts cause index fragmentation at scale.

UUID Generator

Generates RFC 4122 version 4 (random) UUIDs using the browser's cryptographically secure `crypto.randomUUID()` API. Choose the number to generate (1–100), uppercase or lowercase output, and whether to include hyphens. UUIDs are used as unique database record identifiers, session tokens, correlation IDs, and file names.

Runs entirely in your browser — your input is never uploaded, stored, or logged.

Generate cryptographically random UUIDs in the format your project requires. For bulk key provisioning, try the Token & API Key Generator.

How to Use

1Click Generate to create one or more UUID v4 values.
2Set the quantity to generate multiple UUIDs at once.
3Copy individual UUIDs or the full list.
4All UUIDs are generated locally in your browser using the Web Crypto API.

Common Uses

→Generate a UUID v4 for a new database record
→Create multiple UUIDs for bulk data seeding or testing
→Copy a UUID for use in mock data or fixtures
→Generate a unique identifier for client-side use

Examples

Single UUID

Input

(click Generate)

Output

f47ac10b-58cc-4372-a567-0e02b2c3d479

Frequently Asked Questions

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