UUID / ULID Generator

UUID / ULID Generator

This tool generates three kinds of unique identifiers — UUID v4, UUID v7, and ULID — in batches of up to 100 at a time. UUID v4 is fully random; UUID v7 follows RFC 9562, packing a millisecond Unix timestamp into the leading 48 bits so IDs sort in creation order; and ULID encodes a 48-bit timestamp plus 80 random bits into 26 characters of Crockford Base32.

Time-sortable identifiers like v7 and ULID are well suited as database primary keys. Random v4 values scatter across the index, whereas time-based IDs keep insertion order and sort order aligned, improving index locality. ULID's Crockford Base32 omits I, L, O, and U to reduce misreads, is case-insensitive, and sorts lexicographically in the same order as time.

For UUIDs (v4/v7) you can toggle uppercase output and hyphen removal, while ULID keeps its standard notation. Every identifier is generated with the browser's Web Crypto API (cryptographically strong randomness), making it hard to predict, and nothing is sent to a server.

How to use

1. Pick UUID v4, UUID v7, or ULID from the tabs at the top. Choose v4 when you need pure randomness, or v7/ULID when you need time-ordered sorting.
2. Enter how many you need (up to 100) in the count field. For UUIDs, toggle Uppercase and Remove hyphens to match your desired output format.
3. The generated values are listed, one per line, in the results area. Copy them all at once with the copy button, or click Regenerate to produce a new set.

Frequently asked questions

Should I use UUID v4 or v7?

Use v4 when you only need unpredictability, and v7 when values should sort by creation time, such as database primary keys. Because v7 carries a timestamp up front, it offers better index locality and insert performance.

How does ULID differ from UUID v7?

Both are time-sortable, but ULID is shorter at 26 Crockford Base32 characters, case-insensitive, and convenient for URLs and filenames. UUID v7 uses the standard 36-character hyphenated UUID format, so it's compatible with existing UUID systems.

Is the randomness secure?

Yes. It relies on the browser's Web Crypto API (crypto.randomUUID / getRandomValues), a cryptographically strong random source that is far harder to predict than plain Math.random.

Do the uppercase and hyphen options apply to ULID?

No. Uppercase conversion and hyphen removal apply only to UUIDs (v4/v7). ULID keeps its standard uppercase Crockford Base32 notation.

Are the values sent to a server?

No. Every identifier is generated in your browser and never sent to a server.