ULID generator
Generate random Universally Unique Lexicographically Sortable Identifier (ULID).
Enable JavaScript to use the interactive tool. The guide below explains how it works.
ULID Generator: Universally Unique Lexicographically Sortable Identifier
In modern distributed systems, choosing the right unique identifier is a critical architectural decision. Traditional auto-incrementing integers fail in distributed environments, and random UUIDv4 identifiers can lead to significant database performance bottlenecks. The ULID (Universally Unique Lexicographically Sortable Identifier) was designed to solve these exact problems, combining the best of both worlds: global uniqueness and chronological sortability.
1. What the Tool Does
The ULID Generator provides an instant way to create high-quality ULIDs for your projects. With a single click, you can generate one or multiple identifiers that are guaranteed to be unique and time-ordered. The tool also allows you to see the underlying components of the ULID (timestamp and randomness) and provides one-click copying for seamless integration into your code or database.
2. Why Professionals Use ULID
- Database Performance: Because ULIDs are time-sortable, they allow databases (like MySQL, PostgreSQL, and MongoDB) to insert new records at the end of the index. This prevents "index fragmentation" and drastically improves write performance compared to random UUIDs.
- Natural Ordering: You can sort records chronologically using the ID itself, without needing a separate
created_atcolumn in many cases. - Human-Friendly Encoding: ULIDs use Crockford's Base32 encoding, which is case-insensitive and avoids ambiguous characters (like I, L, O, and U) to reduce human error.
- No Central Coordinator: Unlike auto-incrementing IDs, ULIDs can be generated independently across multiple servers without risking collisions or needing a central database to coordinate.
3. Step-by-Step Instructions
- Navigate to the ULID Generator tool.
- The tool automatically generates a fresh ULID upon loading.
- If you need multiple IDs, adjust the Count or Quantity setting (if available).
- Click the Generate button to create a new batch of ULIDs.
- Click the Copy icon next to any generated ULID to save it to your clipboard.
- Use the Clear button to remove the generated list and start over.
4. Examples
- A Single ULID:
01ARZ3NDEKTSV4RRFFQ69G5FAV - Sorted Batch:
01ARZ3NDEKTSV4RRFFQ69G5FAV(Generated first)01ARZ3NDEKTSV4RRFFQ69G5FBW(Generated milliseconds later)
5. FAQs
Q: How is a ULID structured? A: A ULID is a 128-bit identifier. The first 48 bits represent a UNIX timestamp in milliseconds, and the remaining 80 bits are cryptographically secure random data.
Q: Is ULID better than UUIDv4? A: For database primary keys, yes. UUIDv4 is completely random, which causes "page splits" and slow inserts in B-tree indexes. ULID's sortability eliminates this issue.
Q: Can I decode the time from a ULID? A: Yes, because the first part is a timestamp, you can always extract the exact millisecond it was created.
6. Common Mistakes
- Using ULID for Security Tokens: Since the timestamp is decodable, don't use ULIDs for things like password reset tokens where you want to hide when the token was created. Use a completely random UUIDv4 instead.
- Assuming Case Sensitivity: ULIDs are designed to be case-insensitive. While they are usually shown in uppercase,
01arz...is technically the same as01ARZ....
7. Real-World Use Cases
- Microservices Architecture: Assigning unique IDs to events in an event-sourced system where chronological order is vital.
- Log Aggregation: Using ULIDs as log entry IDs to ensure logs from different services can be merged and sorted perfectly.
- E-commerce: Generating order numbers that are unique across global regions but still sortable by date.
8. Related Tools
- UUID Generator: For when you need a completely random, non-sortable identifier.
- Date-Time Converter: To help decode the timestamp found inside your ULIDs.
Future-proof your data with identifiers that respect time.