ULID Generator
Generate lexicographically sortable ULIDs with Web Crypto. Bulk create up to 100, copy one or all, toggle uppercase, and decode the embedded timestamp from a pasted ULID. Everything runs in your browser — nothing is sent to a server.
ULID generator controls
Decode timestamp from ULID
How it works
A ULID is a 26-character identifier in Crockford’s Base32. The first 10 characters encode a Unix millisecond timestamp; the remaining 16 are random (via Web Crypto). Lexicographic order matches creation time, and the alphabet avoids ambiguous characters such as I, L, O, and U.
Generate one or many (up to 100), toggle uppercase, and copy a single ULID or the full list. The decode panel extracts the embedded timestamp from a pasted ULID for debugging and audits.
No ULID text is sent to Formattly — generation and decoding run only in your browser tab.
When to use this tool
- Sortable public IDs that should be URL-safe and case-insensitive
- Alternatives to UUID when you prefer 26-character Base32 over hex hyphenated form
- Fixture data for APIs that already standardize on ULID
- Recovering approximate creation time from a stored ULID
Tips
- Compare with UUID v7 if your stack expects RFC 9562 UUIDs
- Uppercase is common in docs; lowercase usually sorts the same in Base32
- Rejects obviously invalid lengths or characters in the decode box
Frequently asked questions
What is a ULID?
A ULID (Universally Unique Lexicographically Sortable Identifier) is a 26-character ID encoded in Crockford's Base32. The first 10 characters encode a Unix timestamp in milliseconds; the remaining 16 are random. ULIDs sort by creation time and are URL-safe.
How does ULID compare to UUID v7?
Both are time-ordered unique IDs. UUID v7 (RFC 9562) is 128-bit hex with standard UUID formatting. ULID uses Crockford Base32 (26 chars), is case-insensitive, and avoids ambiguous characters (I, L, O, U). Choose based on ecosystem preferences — databases and APIs may favor one or the other.
Does my ULID data leave my browser?
No. Generation and timestamp decoding run entirely in your browser with JavaScript and Web Crypto. Nothing is uploaded to a server.
Is this ULID generator free?
Yes. The Formattly ULID Generator is free to use with no signup required.
Are ULIDs case-sensitive?
Crockford Base32 is designed to be case-insensitive. This tool can emit uppercase or lowercase for convenience; treat them as the same ID when comparing in case-insensitive contexts.