About the UUID / GUID Generator (v4)
A UUID (Universally Unique Identifier), also called a GUID, is a 128-bit identifier designed so that two independently generated values are, for all practical purposes, guaranteed never to collide. Version 4 UUIDs are generated using random or pseudo-random numbers and are the most common type used in databases, distributed systems, session tokens and API keys today. This generator creates real, cryptographically strong version 4 UUIDs using your browser's built-in secure random number generator.
This tool is useful for backend developers who need primary keys or correlation IDs, frontend developers generating unique React keys or component IDs, QA engineers creating test fixtures, and DevOps engineers needing unique identifiers for infrastructure resources. Since generation happens locally using the Web Crypto API, there's no network round-trip and no risk of predictable or logged values.
To use it, choose how many UUIDs you want (from 1 to 1,000), and optionally choose the format: standard lowercase with dashes (like 550e8400-e29b-41d4-a716-446655440000), uppercase, or without dashes. Click "Generate" and the list appears instantly. Use the copy button to grab a single value or all of them at once, or download the full list as a text file for bulk use in scripts or database seeding.
For example, generating 5 UUIDs might produce values like 9b1deb4d-3b7d-4bad-9bdd-2b0d7b3dcb6d and 3c1a1e0e-2c92-4c93-9a30-6d5b1eaf9d21 — each one statistically unique thanks to 122 random bits (the remaining 6 bits encode the version and variant per the UUID specification).
A common misconception is that UUIDs must come from a database or server to guarantee uniqueness — in reality, version 4 UUIDs rely purely on randomness, and the probability of a collision is astronomically small (you would need to generate around a billion UUIDs per second for around 85 years to have a 50% chance of a single collision). This makes them perfectly safe to generate client-side for most applications, including primary keys, idempotency tokens, and file names.
Tip: while UUIDs are great for uniqueness, they are not sequential, which can hurt database index performance at very large scale compared to auto-incrementing IDs or time-ordered identifiers like UUID v7 or ULIDs — something worth considering for high-throughput systems, though for the vast majority of applications version 4 UUIDs remain the simplest and most portable choice.