Integers, UUID, GUID, CUID and NanoID Explained

When creating or designing databases, unique identifiers are going to be needed.

Choosing one can impact how well your database performs, how easily it can grow, and how simple it is to work with.

In this article, we'll explore several options for automatically generated IDs, explain what they are, their benefits and drawbacks, and share the advantages of each.

Auto-Incrementing Integers

This method involves starting at 1 and increasing the number by 1 for each new record. It's straightforward and easy to understand, which is why we love it and use it.


  • Simplicity: The concept and implementation of auto-incrementing integers are simple, making them easy to understand and use in database management.
  • Performance: In many database systems, auto-incrementing integers as primary keys can benefit performance since it's the smallest option. This speeds up query operations that involve looking up, inserting, or deleting records based on the identifier.
  • Predictability: The sequential nature of auto-incrementing integers offers predictability in the order of record creation, which can benefit sorting and data organization.


It's best for simpler applications or those with less stringent requirements on identifier format and uniqueness across systems. Or apps/systems where performance is more important than uniqueness.


UUIDs and GUIDs are essentially the same thing. They serve as a standard for generating unique identifiers. They are 128-bit long and comply with a specific standard (RFC 4122), which means they are unique across billions of devices and epochs.

It is potentially an oversimplification, but "GUID" is just the name Microsoft uses for its UUID version.


  • Universality and Compatibility: UUIDs can be generated on any machine without a central coordinating authority, making them perfect for distributed systems.
  • Low Collision Probability: The architecture of UUIDs and GUIDs ensures an extremely low chance of identifier collision, making them dependable for maintaining uniqueness in vast systems.


Since UUIDs consume the most space to store, situations require a high level of uniqueness, but when performance is not the most critical thing.


CUID is a more modern approach to generating unique identifiers, designed to be more collision-resistant than UUIDs.

CUIDs are shorter, making them more efficient to use in databases and easier to handle in URLs.

They are also sequential to a degree, which can help with database indexing performance.


  • Improved Collision Resistance: Better algorithm for reducing the chances of identifier duplication.
  • Performance: Designed to be database-friendly, improving indexing efficiency.


It's best for making websites and online apps where you need to efficiently use many unique codes. It's my usual go-to.


NanoID generates very compact, URL-friendly IDs that are still very unlikely to clash with one another. Unlike the others in the list, it's customizable, which can make it flexible for certain use cases.


  • Flexibility: Customizable alphabet and size.
  • Security: Uses secure random APIs to generate IDs, providing high unpredictability.


Best for projects that need short, safe codes that are easy to share, like link shorteners.

Still want to learn more?

For those looking to dive deeper into the specifics of UUID, GUID, CUID, and NanoID, here are some useful resources:

  • RFC 4122 details the standards for UUIDs, covering their structure, generation methods, and unique features. It's a difficult read, but it's good if you want to go down the rabbit hole.

To look at the design principles and documentation for CUID and NanoID, their official GitHub repositories are great:

Avatar for Niall Maher

Written by Niall Maher

Founder of Codú - The web developer community! I've worked in nearly every corner of technology businesses; Lead Developer, Software Architect, Product Manager, CTO and now happily a Founder.


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