mkulid

A command-line ULID generator — like uuidgen, but for ULIDs.

Why

I needed sorted, random identifiers in shell scripts and pipelines. I couldn't find a standalone ULID CLI, so I wrote one.

If you don't specifically need ULIDs, UUID v7 is a similar time-sortable alternative — though its spec leaves sub-millisecond ordering as an implementation choice rather than mandating strict monotonicity.

Installation

From crates.io

cargo install mkulid

From GitHub releases

Pre-built binaries are available on the Releases page. Download the archive for your platform, extract it, and place the mkulid binary somewhere on your PATH.

Usage

Generate a single ULID:

$ mkulid
01JMCX2F5GKQJ3YZT4BXNRP8WH

Generate a batch of five (monotonically ordered):

$ mkulid -n 5
01JMCX2F5GKQJ3YZT4BXNRP8WH
01JMCX2F5GKQJ3YZT4BXNRP8WJ
01JMCX2F5GKQJ3YZT4BXNRP8WK
01JMCX2F5GKQJ3YZT4BXNRP8WM
01JMCX2F5GKQJ3YZT4BXNRP8WN

Lowercase output:

$ mkulid -l
01jmcx2f5gkqj3yzt4bxnrp8wh

Pin the timestamp to a specific Unix epoch value (milliseconds):

$ mkulid --timestamp 1716214200123
01HYG2ZS1VKQJ3YZT4BXNRP8WH

Pin the timestamp to an RFC 3339 datetime:

$ mkulid --datetime "2024-05-20T14:30:00Z"
01HYG2ZS00KQJ3YZT4BXNRP8WH

Inspect an existing ULID:

$ mkulid --inspect 01JMCX2F5GKQJ3YZT4BXNRP8WH
ULID:      01JMCX2F5GKQJ3YZT4BXNRP8WH
Timestamp: 2025-02-13T12:34:56.789+00:00
Unix ms:   1739446496789
Random:    0x003a7b4e5f6c8d9e0a1b

Development

Building from source requires a Rust toolchain (1.85+, edition 2024).

git clone https://github.com/jakobwesthoff/mkulid.git
cd mkulid
cargo build --release

The binary will be at target/release/mkulid.

To install directly from a local checkout:

cargo install --path .

License

MPL-2.0