The Complete Guide to ULIDs: Why You Should Upgrade from UUIDs

If you’ve spent time building databases or distributed systems, you’re likely familiar with UUIDs. While UUIDs are excellent for generating unique identifiers without a central authority, they have one major flaw: they are completely random. This randomness can lead to fragmented database indexes and poor insertion performance.

Enter ULID (Universally Unique Lexicographically Sortable Identifier). ULIDs solve the sorting and database indexing issues of UUIDs while maintaining the same level of uniqueness. In this guide, we'll explain what ULID is, why it's a great alternative to UUID, and how to use our ULID Generator tool.

What is a ULID?

A ULID is a 128-bit identifier, just like a UUID, but it is specifically designed to be sortable. It achieves this by combining a timestamp with a random component.

Format of a ULID

A standard ULID is represented as a 26-character string, using Crockford's Base32 encoding (which excludes confusing characters like I, L, O, and U).

Example: 01ARZ3NDEKTSV4RRFFQ69G5FAV

This string is composed of two parts:

1. Timestamp (10 characters): A 48-bit integer representing the timestamp in milliseconds. This ensures that ULIDs generated later in time will sort after earlier ones.
2. Randomness (16 characters): An 80-bit random or pseudo-random number, providing the uniqueness.

Why Choose ULID over UUID?

Here are the key reasons developers are migrating from standard UUIDs (like Version 4) to ULIDs:

1. Lexicographically Sortable

Because the first part of a ULID is a timestamp, ULIDs can be sorted alphabetically. This is a game-changer for database performance because your generated IDs naturally append to the end of your indexes rather than being randomly inserted all over the place.

2. Shorter String Representation

A UUID typically uses a 36-character string format (including hyphens). A ULID, thanks to Base32 encoding, only requires 26 characters. This saves storage space and makes the IDs slightly more compact when included in URLs.

3. URL-Safe and Easy to Read

Crockford’s Base32 encoding ensures that ULIDs are URL-safe. Plus, the exclusion of ambiguous characters reduces the chance of human error when reading or copying an ID manually.

4. High Compatibility

Under the hood, a ULID is still 128 bits. This means it can be stored in any database column that currently supports UUIDs (like Postgres's uuid type) simply by converting it to the UUID format!

How to Use Our ULID Generator

If you need a quick ULID for testing, seeding a database, or integrating into your app, our tool makes it effortless.

1. Open the tool: Go to the ULID Generator Tool.
2. Select Quantity: Choose how many ULIDs you want to generate (e.g., 1, 10, or 100).
3. Generate: Click the "Generate" button.
4. Copy and Use: Quickly copy individual ULIDs or the entire list using the handy copy buttons.

Generating ULIDs in Code

If you need to generate ULIDs programmatically, there are libraries available in almost every major programming language.

JavaScript / Node.js:

import { ulid } from 'ulid';

const myULID = ulid();
console.log(myULID);

Python:

import ulid

my_ulid = ulid.new()
print(my_ulid.str)

Java:

import com.github.f4b6a3.ulid.UlidCreator;

String ulid = UlidCreator.getUlid().toString();
System.out.println(ulid);

Conclusion

If you're starting a new project or looking to optimize a database that currently suffers from index fragmentation due to random UUIDs, give ULIDs a try. They offer the exact same uniqueness guarantees while providing massive improvements to sorting and database insert performance.

Generate your first batch of sortable IDs now using our free ULID Generator!

Check out our other developer tools:

• UUID Generator: Generate standard v1, v4, or v7 UUIDs.
• JSON Formatter: Validate and beautify your JSON data.
• Base64 Encoder/Decoder: Convert data to Base64 strings.