mockstack.

UUID Generator

v1 · v4 · v7 · ULID ← Developer & Data

UUIDs, ULIDs, and NanoIDs in bulk, or paste one to see what is inside it.

Generated
Inspect
READY RUNS LOCALLY

About the UUID Generator

Generates unique identifiers in every common flavor, in bulk, in your browser, and decodes any identifier you paste into the inspector.

Every Setting

Kind
v4 is purely random, the everyday default. v7 is time-ordered, which keeps database indexes fast. v1 encodes time plus a node id, the legacy form of the same idea. v5 and v3 are name-based: the same input always produces the same id (v5 uses the stronger hash). ULID is a compact, sortable alternative; NanoID is shorter still for URLs; Nil is the all-zero placeholder.
Name
The input for the name-based kinds, hashed together with a namespace to make the deterministic id.
Count
How many to list, up to 200. Raising it adds new IDs at the end and lowering it trims from the end; the rest stay as they are.
Format
Lowercase or uppercase, with or without dashes, plain or wrapped: {Braces} for the Windows registry and .NET style, "Quotes" or 'Quotes' to paste into code or SQL, or urn:uuid: for the formal URN. Comma Separated puts a comma after each one but the last, ready for a list or an IN (…) clause. These combine freely and restyle the IDs already listed rather than making new ones. ULID and NanoID have one fixed form, so the settings gray out for those.
Generate
Deals a fresh batch. Choosing another version, or changing the namespace or name, also makes new IDs; format settings never do.
Copy All / Download / Text View
The batch as a clipboard copy, a text file, or a plain list for selecting by hand. Click any single id in the grid to copy just that one.
Inspect
Paste any identifier and it names the version and, where one exists, decodes the creation time out of it.

Common Questions

Random or time-ordered?
Random for general use; time-ordered when the ids become database keys, because inserts stay sequential.
Can two ever collide?
The random space is so large that collisions are a theoretical concern, not a practical one.

Related: Hash Generator, Base64 and URL Encoder.