ULID Generator

Generate ULIDs - Universally Unique Lexicographically Sortable Identifiers with timestamp and random components.

1. Click "Generate ULID" to create a single new ULID with a timestamp encoded from the current moment. 2. To generate multiple ULIDs at once, enter the desired count in the bulk generation field and click "Generate Batch." 3. Review the decoded timestamp shown alongside each ULID to verify the embedded creation time. 4. Click the copy button next to any ULID to copy it to your clipboard for use as a database key or identifier. 5. Use the format toggle to switch between the standard 26-character Crockford Base32 representation and the UUID-compatible format.

About This Tool

The ULID Generator creates Universally Unique Lexicographically Sortable Identifiers, a modern alternative to UUIDs that combines a timestamp with randomness. ULIDs are 128-bit values encoded as 26-character strings using Crockford Base32, making them URL-safe, case-insensitive, and naturally sortable by creation time.

ULIDs solve a key limitation of UUIDv4 - they are monotonically sortable. Because the first 48 bits encode a millisecond-precision timestamp, ULIDs generated later always sort after earlier ones. This makes them ideal for database primary keys where insertion order matters for performance, especially in distributed systems.

Generate single ULIDs or bulk batches, and see the decoded timestamp for each. The tool also compares ULIDs to UUIDs, showing the advantages for different use cases. All generation happens in your browser using the Web Crypto API for the random component.

Frequently Asked Questions

A ULID (Universally Unique Lexicographically Sortable Identifier) is a 128-bit identifier like a UUID, but with a key difference: the first 48 bits are a timestamp, making ULIDs naturally sortable by creation time. UUIDs v4 are completely random and have no inherent ordering.

Use ULIDs when you need sortable identifiers, especially for database primary keys in time-series data, event logs, or distributed systems where insertion order matters for index performance. Use UUIDs when you need maximum compatibility with existing systems.

ULIDs are 128 bits like UUIDs and can be stored in UUID columns by converting to the standard UUID format. Many ULID libraries provide conversion functions. They can also be stored as their native 26-character string representation.

ULIDs use 80 bits of randomness (the lower portion), providing 2^80 possible values per millisecond. This is less random than UUIDv4 (122 random bits) but still more than sufficient for practical uniqueness in any real-world system.

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