ULID Generator

ULID Generation Options

Generated ULIDs

ULID Decoder & Validator

About ULID

ULID (Universally Unique Lexicographically Sortable Identifier) is a 128-bit identifier with millisecond precision timestamps and lexicographic sorting capability.

ULID Structure

ULID format (26 characters):

01AN4Z07BY79KA1307SR9X4MV3
  • Timestamp: 48-bit (10 chars)
  • Randomness: 80-bit (16 chars)
  • Encoding: Crockford Base32
  • Case insensitive, URL-safe
ULID Advantages
  • 📅 Chronologically Sortable
  • 🔗 URL-Safe Characters
  • 🎯 Case Insensitive
  • ⚡ No Special Characters
  • 🔄 Monotonic Sort Order
Common Use Cases
  • 🗄️ Database Records
  • 📊 Event Sourcing
  • 📋 Log Entries
  • 🔗 API Resources
  • 📱 Mobile Apps
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Professional ULID Generator - Lexicographically Sortable Identifiers

Generate ULIDs (Universally Unique Lexicographically Sortable Identifiers) with timestamp precision and natural sorting capabilities. Perfect for distributed systems, databases, and applications requiring chronological ordering.

What is ULID?

ULID is a 128-bit identifier specification that combines the uniqueness of UUIDs with the chronological ordering benefits of timestamps. Unlike UUIDs, ULIDs are lexicographically sortable, making them ideal for time-series data and database indexing.

ULID Features

  • 128-bit compatibility with UUID storage
  • 1.21e+24 unique ULIDs per millisecond
  • Lexicographically sortable chronologically
  • Canonically encoded as 26 character string
  • Uses Crockford Base32 for better readability
  • Case insensitive and URL-safe
  • No special characters (-, _, etc.)

ULID vs UUID Comparison

  • Sorting: ULIDs are naturally sortable, UUIDs are not
  • Timestamp: ULIDs include millisecond timestamp, most UUIDs don't
  • Readability: ULIDs use Base32, UUIDs use hexadecimal
  • Length: ULIDs are 26 characters, UUIDs are 36 characters
  • Performance: ULIDs offer better database indexing performance

Best Practices for ULID Usage

  • Use ULIDs for time-series data and event sourcing
  • Perfect for database primary keys requiring chronological order
  • Ideal for distributed systems with multiple generators
  • Store as binary (128-bit) for optimal database performance
  • Use canonical uppercase format for consistency
  • Consider monotonic ULIDs for same-millisecond generation

ULID Applications

  • Database primary keys with natural ordering
  • Event sourcing and audit trails
  • Log aggregation and analysis systems
  • Distributed system correlation IDs
  • API resource identification
  • Mobile application offline sync

ULID Questions

Both are 128-bit unique IDs. The key difference is that ULIDs sort lexicographically by time — newer IDs come after older ones. They're also shorter (26 chars vs 36) and use Base32 instead of hex. Handy when you want IDs that naturally order by creation time.

When ordering matters. Event logs, audit trails, database records where you'd otherwise need a "created_at" column for sorting. ULIDs give you that for free. They're also nicer in URLs — no hyphens, case-insensitive.

Yes, they're both 128 bits. Most ORMs can convert between them. Just know that you'll lose the sorting benefit once it's stored as a UUID — the byte ordering is different.

Millisecond precision. The timestamp covers dates from 1970 through roughly the year 10889, so you're set for a while.