CUID Generator - Generate Collision-Resistant Unique IDs

About CUID

CUID stands for Collision-resistant Unique IDentifier. It was created by Eric Elliott as a solution for generating unique IDs in distributed systems where traditional auto-incrementing IDs don't work well.

Each CUID contains the following components:

c - A constant prefix indicating it's a CUID
Timestamp - 8 characters of base36-encoded milliseconds
Counter - 4 characters to prevent same-millisecond collisions
Fingerprint - 4 characters derived from machine/process info
Random - 8 random characters for additional uniqueness

Use Cases for CUID

Primary keys in distributed databases
Session IDs and tokens
URL slugs and permalinks
File and resource identifiers
Event tracking and analytics
Cache keys in distributed caching systems

Frequently Asked Questions

How is CUID different from other ID formats?

CUID uses a combination of a timestamp, counter, machine fingerprint, and random data to ensure uniqueness, even when generated simultaneously on different machines. This makes it ideal for distributed systems in which coordinating servers is impractical.

How long is a CUID?

A CUID is always 25 characters long. It begins with the letter "c" followed by 24 alphanumeric characters (lowercase letters and numbers only).

Can I use CUID in a databases?

Yes! CUIDs are excellent for database primary keys, especially in distributed databases. They are sortable by creation time, don't require central coordination, and are more human-readable than UUIDs.

Is CUID sortable?

Yes, CUIDs can be roughly sorted by creation time because they include a timestamp. Generally, IDs generated later will sort after earlier ones. However, this isn't guaranteed for IDs generated within the same millisecond on different machines.

How can I generate multiple CUIDs at once?

Specify how many CUIDs you need (up to 100) using the count input above, then click Generate. You can then copy all of the generated IDs or download them as a text file.