UUID & ID Generator
Generate UUID v4, v7, ULID and Nano ID — and inspect any UUID you have.
About the UUID Generator
Generate up to a thousand identifiers at once in four formats, and inspect any UUID you already have for its version, variant and — for v1 and v7 — the creation time embedded in it. The choice that matters is v4 against v7: a v4 UUID is random throughout, so it tells nobody when it was made but scatters inserts across a database index; a v7 UUID leads with a millisecond timestamp, so rows append in order at the cost of disclosing their creation time. ULID makes the same trade as v7 in a 26-character base32 form that sorts correctly as plain text. Every value comes from the browser's cryptographic random source, and if that source is unavailable the tool says so rather than quietly substituting a weaker one.
Are these generated on a server?
No. Every ID is produced in your browser from its own cryptographic random source, so nothing is transmitted and no two visitors can receive the same list.
Should I use v4 or v7?
v7 for anything stored in a database, because its leading timestamp means inserts land at the end of the index rather than at random points in it — which is measurably cheaper at scale. v4 when you specifically want an identifier that reveals nothing about when it was made.
Does a v7 UUID leak information?
It encodes the millisecond it was created, to a precision anyone holding the ID can read. That is the trade for sortability. If creation time is sensitive, use v4.
What is the difference between UUID v7 and ULID?
Both are a timestamp followed by randomness. A UUID v7 is 36 hex characters with dashes and fits any UUID column; a ULID is 26 base32 characters that sorts correctly as plain text. Pick ULID when the ID travels as a string, v7 when it goes into a UUID type.
Can two of these collide?
Not in practice. A v4 UUID has 122 random bits, and ULID and Nano ID are comparable — you would need an impractical number of IDs before a collision became likely. This is why no coordination with a server is needed.
Is a UUID safe to use as a secret?
A v4 UUID is unguessable enough to act as a capability token, but v1 and v7 are not — their timestamps make a large part of the value predictable. For anything security-bearing, prefer a purpose-made random token.
Related: Hash Generator · Timestamp Converter · JSON Formatter
Keywords: uuid generator, guid generator, uuid v4, uuid v7, ulid, nanoid, bulk uuid, uuid version checker