ULID Generator

ULID Generator: Create Unique Sortable Identifiers Online

Generate ULIDs instantly with our free online ULID generator tool. Create Universally Unique Lexicographically Sortable Identifiers that combine timestamps with cryptographically secure random data for database keys, distributed systems, and web applications.

What is a ULID Generator?

A ULID (Universally Unique Lexicographically Sortable Identifier) is a unique identifier system that combines a timestamp with random data to create a 26-character string. Unlike traditional UUIDs, ULIDs are lexicographically sortable while maintaining cryptographic uniqueness and randomness, making them ideal for modern distributed applications.

How to Generate ULID Identifiers

Our ULID generator tool creates unique identifiers instantly:

Click Generate: Use our online tool to create new ULIDs
Copy Results: Get your unique 26-character identifier
Use Anywhere: Implement in databases, APIs, or applications

ULID Structure and Format

Understanding ULID Components

A ULID identifier structure consists of two main parts:

Timestamp (10 characters): The first 10 characters represent the time in milliseconds since the Unix Epoch (1970-01-01).
Randomness (16 characters): The remaining 16 characters are generated using cryptographically secure random data.

The resulting 26-character string is encoded using Crockford's base32 alphabet (0-9 and A-Z, excluding I, L, O, and U).

Formula

The ULID is generated using the following steps:

Generate a 48-bit timestamp (milliseconds since Unix Epoch).
Generate 80 bits of cryptographically secure random data.
Encode the combined 128 bits using Crockford's base32 encoding.

Calculation

The ULID generator performs the following steps:

Get the current timestamp in milliseconds.
Generate 10 random bytes (80 bits) using a cryptographically secure random number generator.
Combine the timestamp and random data into a 128-bit integer.
Encode the 128-bit integer using Crockford's base32 encoding.

ULID Use Cases and Applications

ULID generators are essential for modern software development across multiple scenarios:

Database Applications

Primary keys: Replace auto-incrementing IDs with sortable ULIDs
Sharding: Distribute data across multiple databases efficiently
Indexing: Improve database performance with naturally sorted identifiers

Distributed Systems

Microservices: Generate unique IDs without central coordination
Event sourcing: Create sortable event identifiers across services
Message queues: Tag messages with chronologically ordered ULIDs

Web Development

API endpoints: Create URL-friendly identifiers for REST APIs
Session tracking: Generate secure session IDs for user management
File uploads: Name files with unique, sortable identifiers

ULID vs UUID: Key Differences

Feature	ULID	UUID
Sortability	Lexicographically sortable	Not sortable
Timestamp	Includes millisecond timestamp	No timestamp (v4)
Length	26 characters	36 characters (with hyphens)
Encoding	Crockford's Base32	Hexadecimal
Case Sensitivity	Case insensitive	Case insensitive

Alternative Unique Identifier Systems

Compare ULID generators with other unique identifier solutions:

UUID (Universally Unique Identifier): Traditional 128-bit identifier without timestamp sorting
KSUID (K-Sortable Unique IDentifier): Similar concept with different timestamp encoding
Snowflake ID: Twitter's distributed system with timestamp and worker ID components

ULID Implementation Examples

Programming Language Support

Implement ULID generation across different programming languages:

JavaScript ULID Generator

1// JavaScript implementation
2function generateULID() {
3  const timestamp = Date.now().toString(36).padStart(10, '0');
4  const randomness = crypto.getRandomValues(new Uint8Array(16))
5    .reduce((acc, byte) => acc + byte.toString(36).padStart(2, '0'), '');
6  return (timestamp + randomness).toUpperCase();
7}
8
9console.log(generateULID());
10

Python ULID Generator

1## Python implementation
2import time
3import secrets
4import base64
5
6def generate_ulid():
7    timestamp = int(time.time() * 1000).to_bytes(6, byteorder="big")
8    randomness = secrets.token_bytes(10)
9    return base64.b32encode(timestamp + randomness).decode("ascii").lower()
10
11print(generate_ulid())
12

Java ULID Generator

1// Java implementation
2import java.security.SecureRandom;
3import java.time.Instant;
4
5public class ULIDGenerator {
6    private static final SecureRandom random = new SecureRandom();
7    private static final char[] ENCODING_CHARS = "0123456789ABCDEFGHJKMNPQRSTVWXYZ".toCharArray();
8
9    public static String generateULID() {
10        long timestamp = Instant.now().toEpochMilli();
11        byte[] randomness = new byte[10];
12        random.nextBytes(randomness);
13
14        StringBuilder result = new StringBuilder();
15        // Encode timestamp
16        for (int i = 9; i >= 0; i--) {
17            result.append(ENCODING_CHARS[(int) (timestamp % 32)]);
18            timestamp /= 32;
19        }
20        // Encode randomness
21        for (byte b : randomness) {
22            result.append(ENCODING_CHARS[b & 31]);
23        }
24        return result.toString();
25    }
26
27    public static void main(String[] args) {
28        System.out.println(generateULID());
29    }
30}
31

These ULID code examples demonstrate implementation across popular programming languages. Adapt these functions for your specific applications or integrate them into larger systems requiring unique identifiers.

Frequently Asked Questions (FAQ)

What is a ULID and how does it work?

A ULID (Universally Unique Lexicographically Sortable Identifier) is a 26-character unique identifier that combines a timestamp with cryptographically secure random data. Unlike UUIDs, ULIDs maintain chronological order when sorted lexicographically.

How do I generate ULID identifiers online?

Use our free ULID generator tool above to create unique identifiers instantly. Simply click the generate button to create new ULIDs, then copy the results for use in your applications.

What's the difference between ULID and UUID?

ULIDs are sortable by creation time, use 26 characters with Crockford's Base32 encoding, and include timestamps. UUIDs are 36 characters (with hyphens), use hexadecimal encoding, and aren't naturally sortable.

Are ULIDs cryptographically secure?

Yes, ULID generators use cryptographically secure random number generation for the 80-bit randomness component, providing high collision resistance while maintaining temporal ordering.

Can I use ULIDs as database primary keys?

Absolutely! ULIDs make excellent database primary keys because they're unique, naturally indexed by creation time, and don't require central coordination in distributed systems.

What encoding does ULID use?

ULIDs use Crockford's Base32 encoding (0-9 and A-Z, excluding I, L, O, U) which is case-insensitive and URL-safe, making them ideal for web applications.

How long are ULID identifiers?

ULIDs are exactly 26 characters long, making them more compact than standard UUIDs (36 characters with hyphens) while providing the same level of uniqueness.

Can ULIDs be generated offline?

Yes, ULID generation works entirely offline since it only requires the current timestamp and a cryptographically secure random number generator - no network connectivity needed.

Why Choose Our ULID Generator?

Instant generation: Create ULIDs immediately without installation
Cryptographically secure: Uses secure random number generation
Copy-ready format: Results are instantly ready for use
Free online tool: No registration or payment required
Cross-platform: Works in any modern web browser

Start generating unique sortable identifiers now with our free ULID generator tool.

Technical References

"ULID Specification." GitHub, https://github.com/ulid/spec. Accessed 2 Aug. 2024.
"Crockford's Base32 Encoding." Base32 Encoding, http://www.crockford.com/base32.html. Accessed 2 Aug. 2024.
"UUID vs ULID." Stack Overflow, https://stackoverflow.com/questions/54222235/uuid-vs-ulid. Accessed 2 Aug. 2024.

ULID Generator - Free Online Unique Sortable ID Creator

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