Exploring Famous Services Using 'ui.' as a Subdomain

Tadashi Shigeoka ·  Tue, October 14, 2025

Recently, I needed to build a showcase site for UI components in a certain project, and the topic of which subdomain to use came up. While docs.example.com and app.example.com are common, since this was a UI-focused site, the idea of using ui.example.com was proposed.

“But wait, are there any famous services that use ui. as a subdomain?”

This question suddenly came to mind, so I decided to do some research. I hope this will be helpful for those thinking about the same thing.

Research Results: Services with ui. Subdomain

I picked several services that I thought were well-known, based on factors like GitHub star counts. To cut to the chase, most of the cases were documentation or showcase sites for UI component libraries.

Here are the services I found.

1. shadcn/ui (ui.shadcn.com)

One of the most popular React component libraries right now. Rather than installing it as a library, it has gained popularity through its innovative approach of copying and pasting the code of components you need into your own project. Its official site is ui.shadcn.com.

2. TOAST UI (ui.toast.com)

A suite of JavaScript UI libraries developed by NHN Corporation in Korea. In particular, the TOAST UI Editor, a WYSIWYG editor, is very well-known and has been adopted by many web services. Its portal site is ui.toast.com.

3. Nuxt UI (ui.nuxt.com)

A UI component library for Nuxt.js, the Vue.js framework. Based on Tailwind CSS, it allows you to quickly build consistent UIs in Nuxt projects. Its documentation site is also ui.nuxt.com.

4. Mantine UI (ui.mantine.dev)

A UI component library for React and Next.js. It provides a rich set of components and hooks, with consideration for accessibility. The official site is hosted at ui.mantine.dev.

5. Lobe UI (ui.lobehub.com)

A Web UI framework provided by LobeHub for building AIGC (AI Generated Content) applications. It offers components that make it easy to create ChatGPT-like UIs. Its official site is also ui.lobehub.com.

6. AWS Amplify UI (ui.docs.amplify.aws)

A UI component library for the Amplify framework provided by AWS. It supports major frontend frameworks and makes it easy to implement UIs that integrate with AWS services. At ui.docs.amplify.aws, this is a slightly unusual subdomain ui.docs, but it does include ui.

Analysis and Summary

As a result of my research, I found that the ui. subdomain tends to be mainly adopted for official sites and documentation of UI component libraries.

  • Clear indication of purpose: Just as docs. indicates a documentation site and app. indicates the web application itself, ui. intuitively shows that the site is a catalog, demo, or documentation for UI components.
  • Branding: Even if the service name itself doesn’t include “UI”, using the ui. subdomain makes it clear that the site is UI-related.

In our project, we also decided to adopt ui.example.com, and these case studies of famous services provided strong evidence to support that decision.

If you’re struggling with subdomain naming and ui. is one of your candidates, these examples should certainly be helpful as a reference.

That’s all from the Gemba.

References