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ULID Generator

What is a ULID Generator?

A ULID Generator is a tool that creates Universally Unique Lexicographically Sortable Identifiers (ULIDs) — 26-character identifiers encoded using Crockford's Base32. ULIDs are designed as a more efficient alternative to UUIDs, offering 128-bit compatibility with UUID while being sortable by creation time.

Each ULID consists of a 48-bit timestamp component (millisecond precision, lasting until approximately 10889 AD) and an 80-bit random component. This design makes ULIDs ideal for distributed systems, database primary keys, and event sourcing where chronological ordering matters. Our free online ULID generator creates IDs entirely within your browser with no server interaction.

Key Features

  • Instant Generation: Generate cryptographically random ULIDs in milliseconds
  • Batch Generation: Create 1 to 100 ULIDs simultaneously with a single click
  • Sortable by Design: ULIDs are lexicographically sortable — newer IDs always come after older ones
  • Dual Output Formats: Choose between raw newline-separated text or formatted JSON array
  • One-Click Copy: Copy all generated ULIDs to clipboard instantly
  • Instant Refresh: Generate new ULID sets with a single click
  • Client-Side Processing: All computation happens in your browser — zero data upload
  • Offline Capable: Works without internet after initial page load

Practical Use Cases for ULIDs

  • Database Primary Keys: Use as sortable primary keys in PostgreSQL, MySQL, and other databases — eliminates the need for auto-increment while maintaining order
  • Distributed Systems: Generate conflict-free identifiers across multiple nodes without central coordination
  • Event Sourcing & Logs: Chronologically sortable IDs make it easy to replay and analyze event streams in order
  • Microservices: Create unique request tracing IDs that can be sorted by time across service boundaries
  • Message Queues: Use as message IDs that preserve temporal ordering
  • Real-Time Applications: ULIDs work well for chat messages, notifications, and activity feeds where chronological ordering is essential

How to Use the ULID Generator

  1. Set Quantity: Use the slider to choose how many ULIDs to generate (1 to 100)
  2. Choose Output Format: Select Raw for newline-separated output (great for bulk copying) or JSON for structured data (ideal for programmatic use)
  3. Copy Results: Click the Copy button to copy all generated ULIDs to your clipboard
  4. Refresh: Click Refresh to generate a new set of ULIDs with updated timestamps

All processing is done locally in your browser. Your data never leaves your device.

Frequently Asked Questions About ULIDs

What is a ULID and how is it different from UUID?
ULID stands for Universally Unique Lexicographically Sortable Identifier. It is a 26-character identifier using Crockford's Base32 encoding. Unlike UUID (which is not sortable by default), ULIDs are designed to be lexicographically sortable because they begin with a timestamp component. ULIDs are also more URL-friendly than UUIDs as they use a case-insensitive character set and avoid special characters. Both offer 128-bit compatibility, but ULIDs are often preferred when chronological ordering is needed.
Are ULIDs truly sortable? How does the timestamp work?
Yes, ULIDs are inherently sortable. The first 48 bits (10 characters in Base32) represent the creation timestamp in milliseconds since the Unix epoch (1970-01-01). This means ULIDs created later will always sort lexicographically after ULIDs created earlier. At millisecond precision, this provides approximately 10 characters of sortable prefix, making them ideal for database indexes and event streams. The timestamp capacity extends to approximately the year 10889 AD.
Can ULIDs be used as database primary keys?
Yes, ULIDs make excellent database primary keys, especially when compared to UUIDs. Their sortable nature means they can be indexed efficiently in B-tree structures without the fragmentation issues that random UUIDs cause. Many databases like PostgreSQL, MySQL, and MongoDB handle ULIDs well. They also provide better cache locality than UUIDs because new inserts are roughly sequential.
What is Crockford's Base32 encoding used in ULIDs?
Crockford's Base32 is a human-readable encoding scheme designed by Douglas Crockford. It uses 32 characters: 0-9 and A-Z (excluding I, L, O, U to avoid confusion with 1, L, 0, and V). The encoding is case-insensitive, making ULIDs easy to communicate verbally and type manually. Unlike base64, Base32 avoids special characters, making ULIDs safe for use in URLs, file names, and database identifiers without escaping.
Is this ULID generator secure and private?
Yes, absolutely. The ULID generator operates entirely within your browser using the cryptographically secure ulid library. All computation happens client-side — no data is sent to any server. The generated ULIDs use high-entropy randomness for the random component (80 bits). After the initial page load, the tool continues to work even without an internet connection, ensuring complete privacy and availability.