ULID Generator — Free Online Tool

ULID Generator: free online tool with examples and documentation. Convert, generate, format, or analyze data instantly in your browser.

Use this free online ULID Generator directly in your browser. No signup required, no data leaves your device. Part of Utilier — a collection of 133+ developer utilities.

What is ULID Generator?

Generates Universally Unique Lexicographically Sortable Identifiers (ULIDs). A ULID is 128 bits encoded with Crockford's Base32, combining a 48-bit millisecond timestamp with 80 bits of randomness. Its string values sort in creation order, which is useful for database keys, logs, and cursors, and monotonic generation keeps same-millisecond values ordered. The embedded timestamp is visible, so choose a fully random ID when creation time is sensitive.

A ULID is a 128-bit identifier whose first 48 bits record a millisecond timestamp and whose remaining 80 bits are random. Its Crockford Base32 representation sorts lexicographically in creation order, which makes it convenient for database keys, logs, and cursors. The timestamp is visible in the value, so use a purely random ID when creation time must remain private.

Why use ulid?

ULIDs combine the uniqueness of UUIDs with time-sortability. They sort chronologically as strings, making them ideal for database primary keys where insertion order matters.

When to use ulid

Use as database primary keys (CockroachDB, DynamoDB), event IDs in event sourcing, log correlation IDs, or anywhere you need globally unique + chronologically sortable identifiers.

How to use ulid

Simple steps to use this tool effectively.

Enter input: Paste or type your input data into the input area. Supports various formats and encodings.
Configure options: Select format, encoding, or other options as needed. Sensible defaults are provided for quick start.
Process data: Click the convert, generate, or format button. Many tools show real-time results as you type.
Review output: Check the output for correctness. Validation errors are shown if any issues are detected.
Copy or export: Click copy button to clipboard or download results as a file for use in your project.
Try examples: Use provided examples to understand features and learn common patterns and use cases.

Key features

Fast processing: Quick and accurate ulid operations with instant results.
Input validation: Validates input format and provides helpful error messages and suggestions for fixes.
Multiple formats: Supports various input and output formats for maximum compatibility and flexibility.
Built-in examples: Includes common use case examples to help you get started quickly and learn.
Copy & export: Easy copying to clipboard or downloading results as files for use in projects.
Real-time updates: See results instantly as you type or change options. No need to click buttons.
Client-side privacy: All processing happens in your browser. No data is uploaded to servers or stored.
Comprehensive docs: Detailed documentation, specifications, FAQs, and troubleshooting help included.

Common use cases

Web development: Use ulid during coding, debugging, and testing web applications.
API integration: Test API requests and responses, validate data formats, debug integration issues.
Data conversion: Convert between different data formats, encodings, or representations as needed.
Learning & education: Understand concepts through interactive examples, experimentation, and documentation.
Documentation: Create clear examples and code samples for technical documentation and guides.
Troubleshooting: Debug issues in development or production by validating, converting, or analyzing data.
Quick prototyping: Rapidly test ideas, generate sample data, or validate approaches without writing code.

Examples

Generate time-sortable unique IDs.

ULID

(generated now)

01H5S7Z8KPQR3YXWMNV0ABCDE

Technical reference

ULID Generator specifications, standards, and technical details.

Standards compliance: Follows industry standards, specifications, and best practices for compatibility and correctness.
Input formats: Supports common input formats used in web development, APIs, and data interchange.
Output formats: Provides multiple output format options for different use cases and requirements.
Character encoding: Handles UTF-8 and other character encodings correctly for international text support.
Browser support: Works in all modern browsers: Chrome, Firefox, Safari, Edge. Requires JavaScript enabled.
Performance: Optimized for fast processing of typical workloads. Large inputs may take longer depending on device.
Security & privacy: Client-side processing only. No data is uploaded to servers, stored, or transmitted externally.
Accuracy: Validated against test suites, specifications, and real-world examples to ensure correctness.
Limitations: Handles typical use cases efficiently. Extremely large inputs (megabytes) may be slower or hit browser limits.
Updates: Regularly updated with new features, improvements, bug fixes, and user-requested enhancements.

Common mistakes to avoid

Clock skew

ULIDs use millisecond timestamps. Clock adjustments or NTP corrections can cause non-monotonic IDs. Use monotonic counters within the same millisecond.

Frequently asked questions

Can I extract the timestamp from a ULID?

Yes. The first 10 characters encode the Unix timestamp in milliseconds (Crockford Base32). You can decode it to know when the ULID was created.

References

Privacy and availability

Runs entirely in your browser — zero server processing
No signup or account required
Works offline once loaded
Fast, lightweight, no external dependencies
Available as a browser extension for Chrome and Firefox

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