Generate standards-compliant, cryptographically strong ULIDs, including true monotonic batches for the same millisecond. Inspect timestamps and 80-bit randomness, convert ULID ↔ raw UUID-formatted 128-bit values, export large batches, and verify lexical ordering locally.
*Monotonic mode prevents duplicates/order reversals inside this generator state until the 80-bit same-millisecond counter would overflow.
This is a bit-preserving representation conversion. The UUID-formatted result does not magically acquire UUID version/variant semantics.
A ULID is 128 bits: a 48-bit Unix timestamp in milliseconds followed by 80 random bits, encoded into 26 Crockford Base32 characters. The canonical first character is limited to 0–7 so the 130-bit text encoding cannot overflow 128 bits.
When multiple ULIDs share one millisecond, monotonic generation increments the random field instead of drawing an unrelated random value, preserving generation order under lexical sorting.
ULIDs are useful when you want compact public IDs that retain chronological locality. Store the canonical 26-character form with a binary/ASCII-safe collation and enforce uniqueness.
Generation and inspection are entirely local. Randomness comes from browser Web Crypto. Remember that a ULID exposes its millisecond creation timestamp by design.