🆔 UUID / GUID Generator
Generate random UUID v4, time-ordered UUID v7 and the NIL UUID. Create up to 100 at once and copy them — everything runs in your browser.
What is a UUID / GUID Generator?
A UUID generator is a free developer tool that creates Universally Unique Identifiers. A UUID is also known as a GUID (Globally Unique Identifier) in the Microsoft ecosystem and shares the same 128-bit structure. A UUID is a 36-character string made of five hyphen-separated groups (xxxxxxxx-xxxx-Mxxx-Nxxx-xxxxxxxxxxxx), where M encodes the version and N the variant. With this tool you can generate random UUID v4, time-ordered UUID v7 and the special NIL UUID in seconds. All generation happens in your browser; the identifiers you create are never sent to a server.
How to use it
- Pick the UUID version you need (v4, v7 or NIL).
- Enter the count (1–100) you want to generate.
- Optionally toggle uppercase, remove dashes, braces or quotes.
- Copy any UUID with its own Copy button, or grab them all with Copy All. Press Regenerate for a fresh batch.
UUID v4 vs v7 vs v1 — which should I choose?
UUID v4 is fully random: 122 bits are filled by crypto.getRandomValues, with the rest reserved for the version (4) and variant. Collisions are effectively impossible, and because it leaks no hardware or timing information it is the most common default. However, being fully random, v4 keys can fragment database indexes with scattered writes.
UUID v7 is a next-generation format standardised in 2024 by RFC 9562. It embeds a millisecond-resolution Unix timestamp in the first 48 bits and fills the rest with randomness, so the IDs are lexicographically sortable by creation time. That produces sequential inserts in B-tree indexes and far better write performance than v4 — making it the ideal choice for modern databases that want a time-ordered primary key.
UUID v1 combines a timestamp with the machine's MAC address. It is sortable like v7, but it exposes the MAC address, raising privacy concerns, and has largely been superseded by v7. That is why this tool offers v7 — the privacy-friendly modern equivalent — instead of v1.
What is the NIL UUID for?
The NIL UUID is a special value with all bits set to zero: 00000000-0000-0000-0000-000000000000. It is used to explicitly represent "not yet assigned", "empty" or "no identifier", and is ideal whenever you need a valid but meaningless UUID placeholder.
Tips
- For database keys, choose v7 when ordering matters and v4 when privacy or full randomness is the priority.
- SQL Server
uniqueidentifiercolumns often expect uppercase, brace-wrapped values; enable those options when needed. - The remove-dashes option is handy when you want the UUID as a compact 32-character hex key (e.g. in a URL or filename).
Frequently Asked Questions
What is a UUID and where is it used?
A UUID is a 128-bit universally unique identifier (also called a GUID). It is used wherever you need uniqueness without a central issuer: database keys, distributed-system records, session tokens and file names.
What is the difference between UUID v4 and v7?
v4 is fully random and carries no ordering. v7 embeds a Unix timestamp at the start, so IDs are sortable by creation time and perform far better in database indexes than random UUIDs.
Are the UUIDs generated by this tool truly unique?
UUIDs use cryptographic randomness from crypto.getRandomValues, with version/variant bits set per RFC 9562. With 122 bits of randomness in v4, the chance of a collision is negligible in practice.
Are my UUIDs sent to a server?
No. All generation happens entirely in your browser; the UUIDs you create are never uploaded or stored. The tool also works offline.