UUID Generator (v4, v7, ULID)
Generate UUID v4, v7, NIL and ULID in bulk — safely from your browser's cryptographic RNG, with uppercase and hyphen options.
UUID v4 — fully random, most common
🔒 Values are generated with your browser's cryptographic RNG and never sent to a server.
Bulk generation, your format
Generate up to 100 UUIDs at once and copy them all in one click — great for test data and example identifiers. Toggle uppercase and hyphens to match your format instantly.
v4 vs v7
v4 is fully random and unordered; v7 embeds the creation time so values sort chronologically, which improves index locality when used as a database key. v7 is part of the 2024 standard (RFC 9562).
ULID and NIL
ULID is a 26-character base32 string that is unique, time-sortable and URL-friendly. NIL is the all-zero UUID used as an empty or default placeholder.
Frequently asked questions
Should I use UUID v4 or v7?
v4 is fine for general identifiers; v7 helps when time-ordering benefits performance, such as database primary keys.
Are generated values sent anywhere?
No. Everything is generated locally with your browser's crypto RNG and never sent to a server.
What is ULID?
A 26-character string combining a timestamp and randomness — unique, sortable and URL-friendly like a shorter UUID.
Can they collide?
v4, v7 and ULID all carry enough random bits that collisions are practically negligible.