ULID generator
Generate sortable ULID identifiers, one per line, straight in your browser.
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ULID generator
Generate ULIDs — universally unique, lexicographically sortable identifiers — one per line, from one up to a thousand at a time. A ULID is 26 characters of Crockford base32: the first 10 encode a 48-bit millisecond timestamp, the remaining 16 carry 80 bits of randomness. The alphabet deliberately skips I, L, O and U, so an id read over the phone or retyped from paper doesn't get mangled.
The timestamp prefix is what sets ULIDs apart from UUIDs. Sort them alphabetically and they come out in creation order, which keeps database indexes compact and range queries cheap — a random UUID v4 scatters inserts across the whole index instead. Within a single batch this generator uses the monotonic strategy: ids created in the same millisecond increment the random part instead of redrawing it, so even a burst of a thousand sorts exactly in generation order.
Three options shape the output. "Count" produces 1 to 1000 ids per run. "Case" switches between the canonical uppercase form and lowercase, which some URL and database conventions prefer — ULIDs are case-insensitive, so both decode identically. "Show timestamp" appends the creation moment decoded from each id as an ISO 8601 date, handy for checking what a stray ULID found in a log actually says.
Everything runs locally in your browser. The randomness comes from crypto.getRandomValues, the platform's cryptographically secure source; nothing is uploaded, no identifier is logged, and the tool keeps working offline once the page has loaded.