A ULID, or Universally Unique Lexicographically Sortable Identifier, is a 26-character identifier format designed to be unique, readable, and sortable by time. It combines a timestamp component with random data so IDs can stay compact while preserving useful ordering behavior.

Why use ULID instead of UUID?

ULIDs are often chosen when you want identifiers that are easier to sort by creation time and easier to read than standard UUIDs. UUIDs are widely supported and standardized, while ULIDs are especially appealing when lexicographic ordering and embedded time information are helpful.

What does monotonic mode mean?

Monotonic mode helps keep generated ULIDs ordered even when multiple IDs are created within the same millisecond. This is useful when you want a sequence of IDs that remains naturally sortable in generation order.

Can I generate multiple ULIDs at once?

Yes. This tool can generate one ULID or create hundreds in one run, which is useful for test data, fixtures, imports, demos, and developer workflows.

Does a ULID include time information?

Yes. ULIDs include a timestamp component, which is one reason they are lexicographically sortable. This tool decodes and shows the timestamp from the first generated ULID so you can inspect it easily.

ULID Generator - Free Online Tool

Generate sortable ULIDs instantly

A ULID Generator creates compact, unique identifiers that are designed to be lexicographically sortable by time.

If you need IDs that are easier to sort and scan than UUIDs, ULID is one of the most practical formats to consider.

This tool lets you:

generate one or many ULIDs at once
switch between uppercase and lowercase output
enable monotonic generation for better ordering within the same millisecond
inspect the timestamp embedded in the first generated ULID
copy the full output in one click

Whether you are building an app, preparing database records, generating fixtures, or exploring sortable ID formats, this tool gives you a quick way to work with ULIDs without writing code.

What a ULID is

ULID stands for Universally Unique Lexicographically Sortable Identifier.

A ULID is designed to solve a common developer need:

generate unique IDs
keep them compact
make them sortable by creation time
avoid the visual bulk of longer identifier formats

A standard ULID is:

26 characters long
built from a timestamp component plus randomness
suitable for lexicographic sorting
easier to read than many longer ID formats

Because the timestamp is embedded into the identifier, ULIDs are often useful in workflows where creation order matters.

Why ULIDs are useful

A lot of identifier systems make trade-offs.

Some are standardized but visually heavy. Some are short but not sortable. Some are sortable but not very portable.

ULIDs are useful because they give you a practical middle ground:

compact enough for everyday use
sortable by time
easy to generate
easy to store
predictable fixed length

This makes them attractive for:

databases
APIs
logs
event streams
test fixtures
public record references
ordered lists of generated entities

What this tool does

This ULID Generator is built for fast everyday workflows.

You can:

generate 1 to 1000 ULIDs in one run
choose uppercase or lowercase formatting
turn Monotonic mode on or off
regenerate instantly when you want a fresh batch
copy the full output list
inspect the first decoded timestamp from the generated results

It is useful for both one-off IDs and bulk developer workflows.

How to use the ULID Generator

1. Choose how many ULIDs to generate

Use the Count field to decide how many ULIDs you want.

Examples:

1 for a single identifier
10 for a small sample set
100 or more for fixtures, imports, QA, or test data

2. Choose uppercase or lowercase output

Enable or disable Uppercase depending on how you want the ULIDs displayed.

This only changes formatting. It does not change the meaning or structure of the identifier.

3. Choose whether to use monotonic mode

Enable Monotonic when you want multiple ULIDs generated in very close succession to remain naturally ordered.

This is useful when you generate many IDs in a burst and still want sorting behavior to reflect generation order as closely as possible.

4. Regenerate when needed

The output updates automatically when you change settings, and you can also click Regenerate to create a fresh set instantly.

5. Copy the results

Use the Copy button to copy the full output list in one click.

Understanding the controls

Count

This controls how many ULIDs are created.

Use smaller counts when:

testing the format
creating one app record
checking output style

Use larger counts when:

generating fixtures
preparing import data
creating sample records
testing ordering behavior

Uppercase

This controls whether the output uses uppercase characters.

Some teams prefer uppercase IDs because they are easier to distinguish visually in logs, spreadsheets, or admin tools.

Others prefer lowercase for consistency with other app identifiers.

Monotonic

This controls whether ULIDs should use monotonic generation.

This is especially useful when several IDs are created within the same millisecond and you still want them to sort in generation order.

Without monotonic behavior, ULIDs generated in the same moment may still be valid and unique, but their relative order may not feel as intuitive in some workflows.

What monotonic ULID means

A standard ULID already contains a timestamp, which makes it sortable by time.

But when several ULIDs are generated within the same millisecond, the timestamp portion alone is not enough to fully represent their order.

That is where monotonic mode helps.

Monotonic ULID generation keeps IDs increasing in a way that preserves more natural ordering within the same timestamp window.

This can be useful for:

rapid inserts into ordered datasets
app events generated in bursts
test runs that generate many IDs quickly
workflows where sorted IDs should reflect generation order more clearly

If ordering behavior matters, monotonic mode is often the better choice.

Understanding the embedded timestamp

One of the most useful properties of ULID is that it includes a timestamp component.

This tool decodes the timestamp from the first generated ULID and shows it in the stats area.

That helps you:

confirm when the ID was generated
understand why ULIDs sort the way they do
inspect the time-based structure of the identifier
compare ULID behavior to UUID or NanoID workflows

For many developers, this timestamp visibility is one of the reasons ULID is appealing.

ULID vs UUID

A common comparison is ULID vs UUID.

UUID is often better when you want:

a widely standardized format
broad interoperability across tools and systems
familiar validation and storage patterns

ULID is often better when you want:

lexicographic sortability by time
a more readable fixed-length format
embedded timestamp behavior
a cleaner-looking identifier for some product workflows

In general:

choose UUID when standardization matters most
choose ULID when ordering and timestamp-aware readability matter more

That is why some teams use UUIDs for compatibility-heavy systems and ULIDs for app-level records, event streams, or ordered identifiers.

ULID vs NanoID

ULID and NanoID solve different problems.

NanoID is useful when you want:

shorter random IDs
flexible length
custom alphabets
URL-safe compact identifiers

ULID is useful when you want:

fixed 26-character length
sortable identifiers
embedded timestamp behavior
predictable lexicographic ordering

If your main goal is compact flexible random strings, NanoID is often the better fit. If your main goal is time-sortable unique IDs, ULID is often the better fit.

Common use cases

Generate sortable database IDs

ULIDs are useful when records benefit from identifiers that sort naturally by creation time.

Create ordered test data

If you want a batch of IDs that preserves time-based order more clearly than random-only formats, ULID is a good choice.

Inspect timestamp-aware identifiers

Because the format includes time information, ULID can be easier to reason about in event-driven or sequence-sensitive systems.

Create bulk fixtures and imports

Need 50, 100, or 500 sortable identifiers for development or QA? Set the count and generate them instantly.

Compare ID strategies during product design

This tool also helps when you are evaluating whether ULID, UUID, or NanoID better matches your application architecture.

Common mistakes and how to avoid them

Assuming uppercase and lowercase are different ULID types

Uppercase vs lowercase is only formatting. The identifier format itself stays the same.

Forgetting why monotonic mode exists

If you generate many ULIDs very quickly, monotonic mode can produce a more useful ordering pattern. Disable it only if you do not care about that behavior.

Treating ULID like a completely random-only string

ULID includes a timestamp component. It is not just a generic random token.

Choosing ULID without checking whether ordering really matters

If you do not need time-based sortability, another format such as UUID or NanoID may be a simpler fit for the workflow.

Why this tool is helpful

You can generate ULIDs in code, but that is often unnecessary for quick everyday tasks.

This tool is useful when you want to:

create one sortable ID quickly
generate many ULIDs for fixtures or sample data
compare uppercase and lowercase output
test monotonic generation behavior
inspect the decoded timestamp visually
copy a ready-made list into a spreadsheet, seed file, JSON payload, or CMS

It removes friction from a very common developer workflow.

Perfect for

developers building apps and APIs
QA teams generating ordered test records
product teams creating sample data
engineers evaluating ID formats
anyone who needs an online ULID Generator

If you need sortable, fixed-length unique identifiers with optional monotonic behavior, ULID is a strong choice.

Generate one or hundreds of ULIDs in seconds, switch uppercase on or off, enable monotonic mode when ordering matters, and inspect the embedded timestamp instantly.