Generate sortable, timestamp-based unique identifiers (ULIDs) in bulk. Includes monotonic mode, custom timestamp seeding, and a built-in decoder. 100% client-side.
100% Free No Signup Instant Results
Configuration
ULID Decoder
0 ULIDs
Generate Sortable ULIDs Online
A ULID is a modern alternative to the UUID that solves one of the UUID's biggest weaknesses: random UUIDs scatter across a database index, hurting write performance and destroying any natural ordering. A ULID fixes this by putting a millisecond timestamp at the front of the identifier, so IDs generated later always sort after earlier ones — while still carrying 80 bits of randomness to stay globally unique.
This generator produces fully spec-compliant ULIDs entirely in your browser. The random portion uses the Web Crypto API for cryptographic quality, and nothing you generate ever touches a server. Create a single ULID, or bulk-generate up to 500 at once for seeding databases, building mock data, or load-testing.
Monotonic Mode, Custom Timestamps & Decoding
Beyond basic generation, this tool includes the advanced features real ULID libraries offer. Monotonic mode guarantees that a batch of ULIDs created in the same millisecond still sorts in exact generation order — essential when you need a stable sequence. You can also seed generation with a custom date and time to produce ULIDs for a specific moment, which is invaluable for testing time-based sorting.
The built-in Decoder works in reverse: paste any ULID and instantly see the exact timestamp embedded in it, converted to a human-readable date, along with its random component. This is a fast way to answer "when was this record created?" straight from its ID, with no database lookup required.
How to use this ULID Generator?
1
Set Options
Choose how many ULIDs to generate and toggle monotonic mode or lowercase output.
2
Generate
Instantly create spec-compliant, sortable ULIDs using the secure Web Crypto API.
3
Copy or Download
Copy a single ULID, copy them all, or download the batch as a .txt file.
4
Decode
Paste any ULID into the decoder to reveal the exact timestamp embedded inside it.
Frequently Asked Questions
A ULID (Universally Unique Lexicographically Sortable Identifier) is a 26-character identifier that combines a 48-bit timestamp with 80 bits of randomness. Unlike a random UUID, ULIDs sort in chronological order, which makes them ideal for database keys where insertion order matters.
Use a ULID when you want globally unique IDs that also sort by creation time (better database index performance and natural ordering). Use a UUID v4 when you specifically want fully random, non-sortable identifiers. ULIDs are also case-insensitive and slightly more compact in text (26 vs 36 characters).
When you generate many ULIDs within the same millisecond, plain generation randomises each one, so their order within that millisecond is not guaranteed. Monotonic mode instead increments the random component by 1, guaranteeing every ULID is strictly greater than the previous — so a bulk batch always sorts in exact generation order.
Yes. The randomness is generated using the browser's Web Crypto API (crypto.getRandomValues), not Math.random. Everything runs locally in your browser, so the identifiers are never sent to or stored on any server.
Yes. Because the timestamp is embedded in the first 10 characters, our decoder can extract the exact creation date and time from any valid ULID. Paste one into the Decoder panel to see its timestamp and random component.