UUID Generator
Generate version 4 UUIDs from your browser's crypto API, up to 100 at a time, with uppercase and no-separator options and one-click copy of the whole list. Runs entirely in your browser.
About this tool
Generates random version-4 UUIDs from your browser's crypto API, up to 100 at a time, with uppercase and no-separator options and one-click copy of the whole list. Every UUID carries the version-4 and variant bits, so it conforms to RFC 4122 and validates anywhere UUIDs are expected. Randomness comes from a cryptographic source, not a seeded pseudorandom generator.
When to use it
Questions
Can two UUIDs collide?
Practically never. A v4 UUID carries 122 random bits, and you would need to generate about 2.7 quintillion UUIDs for a 50% chance of a single duplicate. For any real system, treat collisions as nonexistent.
Are these UUIDs safe to use as secret tokens?
They are unguessable in practice, but they are identifiers, not a credential scheme. Anything security-sensitive — a reset link, an API key — should sit behind a system with expiry and revocation, not just the UUID itself.
What do the uppercase and no-separator options change?
Presentation only. UUID comparison is case-insensitive and the dashes are cosmetic, so both variants are valid — just be consistent if the system you are feeding stores them bare.
What is the difference between a UUID and a GUID?
None in practice — they are two names for the same 128-bit identifier format. GUID is what Microsoft calls it (it is the term in Windows, COM and SQL Server documentation); UUID is the name in the RFC 4122 spec and everywhere else. Both are 32 hex digits, usually hyphenated, and a GUID generator and a UUID generator produce interchangeable values. If a form asks for a GUID, a v4 UUID from this tool is exactly what it wants.
Why generate v4 and not another version?
Because v4 is the only version that gets its uniqueness from pure randomness — 122 random bits — so it needs no clock, no MAC address and no coordination between machines. Version 1 UUIDs embed a timestamp and the device's MAC address, which leaks details you may not want to publish in an API response. v4 is also what this tool generates and what virtually every library's default uuid() call returns, which makes it the safe interchange choice.
Should I use UUID v4 or UUID v7?
V7 was standardized in RFC 9562 (published May 2024); it encodes a millisecond timestamp in its leading bits, and its advantage is real: IDs generated later sort after earlier ones, so database indexes stay compact where random v4 IDs scatter inserts across a B-tree. The trade-off is that v7 exposes creation time to anyone who sees an ID. Keep v4 when IDs are public and should carry no metadata; consider v7 for high-insert database primary keys where sortability matters more. This tool generates v4, which remains the universally accepted default.