UUID Generator
UUID (Universally Unique Identifier) is a 128-bit identifier standardized in RFC 4122. It guarantees global uniqueness without a central coordinating authority, making it ideal for distributed systems, databases, and microservices.
How UUID v4 Works UUID version 4 is generated entirely from random numbers — 122 of 128 bits are filled with a cryptographically strong generator. The probability of a collision (two UUIDs matching) is extraordinarily low: generating one billion identifiers per second for 85 years yields less than a 50% chance of a single collision. UUID format: 8-4-4-4-12 hexadecimal digits (e.g., 550e8400-e29b-41d4-a716-446655440000).
Free online UUID version 4 (random) generator. UUID (Universally Unique Identifier) is a 128-bit identifier that guarantees uniqueness without a central coordinating authority. The UUID standard is defined in RFC 4122 and is widely used in distributed systems where centralized ID generation is impractical.
UUID v4 is generated entirely from random numbers — 122 of 128 bits are filled with a cryptographically strong generator (crypto.randomUUID). The probability of a collision when generating one billion UUIDs per second for 85 years is less than 50%, making the format practically unique for any real-world task.
Create a single UUID with one click or generate a batch of up to 100 identifiers at once. Each UUID can be copied individually, and the "Copy all" button places the entire list in the clipboard. Perfect for developers creating primary keys, session identifiers, tokens, and other unique values.
How to use it
- Press Generate to get a version 4 UUID in the standard 36-character hyphenated form.
- Set a count (up to 100) to get a batch and copy them all at once or one by one.
- Switch the format if needed: uppercase, without hyphens or wrapped in braces.
When it helps
- Database identifiers: fill in test records or hand-create a key for a new entity.
- API keys and session tokens: get a unique value for a configuration or a test stub.
- File and resource names: avoid name collisions when uploading files or creating temporary folders.
Frequently asked questions
How unique is a UUID v4?
It carries 122 random bits. To reach a 50% chance of a collision you would need about 2.7·10¹⁸ identifiers — in practice duplicates do not happen.
How does v4 differ from v1 and v7?
v1 is built from the time and a MAC address, v7 from the time plus random bits (convenient for sorting by creation), v4 is fully random and reveals nothing about its origin.
Can a UUID be a primary key?
Yes, but random v4 values index worse in a B-tree than sequential keys. For large tables UUID v7 or ULID are a better fit.