Generate UUID v4 Online

Generate one or many UUIDs instantly — supports v1, v4, and v5. Bulk generate up to 100 at once.

    What is Generate UUID v4?

    A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit number formatted as a 36-character hexadecimal string with hyphens, such as 550e8400-e29b-41d4-a716-446655440000. Standardized in RFC 4122, UUIDs are designed to be globally unique without a centralized authority. Version 1 derives from a timestamp and MAC address; version 4 is random, generated from 122 cryptographically random bits, and is by far the most common; version 5 is deterministic, hashing a namespace and a name with SHA-1. UUIDs are used as primary keys, distributed system identifiers, idempotency tokens, and correlation IDs across microservices.

    How to use

    1. Select the UUID version (v4 is recommended for most use cases).
    2. Enter how many UUIDs you need (1 to 100) and click Generate.
    3. Copy individual UUIDs or use "Copy all" to get them all at once.

    Frequently asked questions

    What is the difference between UUID v1, v4, and v5?

    UUID v1 is time-based and includes the timestamp and MAC address. UUID v4 is randomly generated and the most commonly used. UUID v5 is name-based using SHA-1 hashing against a namespace.

    Are the generated UUIDs truly unique?

    UUID v4 uses crypto.randomUUID() which provides 122 bits of randomness. The probability of a collision is astronomically low — roughly 1 in 5.3×10^36 for any two UUIDs.

    Can I use UUIDs as database primary keys?

    Yes. UUID v4 is widely used as a primary key in databases. The main trade-off is that random UUIDs can cause index fragmentation in B-tree indexes. UUID v7 (sequential) is often preferred for databases.

    Is UUID the same as GUID?

    UUID and GUID refer to the same concept. GUID (Globally Unique Identifier) is Microsoft's term for UUID (Universally Unique Identifier). The format is identical.

    Last updated

    Powered by maratool