MUI and shadcn/ui are not competing implementations of the same idea. They are opposite answers to one question: who owns the component code. Everything people argue about downstream - theming, bundle size, customisation, upgrades - follows from that, and the choice is easier once you notice you are choosing an ownership model rather than a look.
The two models
MUI owns the code. You install a package, configure a theme, and use components through a documented API. Fixes and accessibility improvements arrive with a version bump, and you customise exactly as much as the API exposes.
You own the code. The shadcn CLI copies source into your repository. There is no version, no upstream, and no API boundary - you edit the file. Nothing arrives on its own, including fixes.
Neither is a compromise position. They are ends of a spectrum, and the middle - wrapping a packaged library to make it yours - usually gets the costs of both.
Which one fits
Team size and turnover. A packaged API enforces consistency without a review process, which matters more as the number of people writing UI grows. Copied source needs a convention people actually follow.
Whether the design is a differentiator. If the interface is the product, an API boundary is a wall you meet weekly. If the interface is a means to an end, that wall is a feature.
Who maintains it. With a package, somebody else fixes the combobox. With copied source, that is you, which the maintenance guide makes concrete: rarely a problem, occasionally a real one.
Existing investment. A theme object, a component library of wrappers and three years of habits are real assets. "Migrating to shadcn" is a rewrite of the visual layer, not a swap.
What migration actually costs
Worth stating plainly, because it is the question behind most searches on this comparison.
Behaviour maps almost one to one. Both sit on similar primitive behaviour, so a dialog is a dialog and a select is a select.
Theming does not map at all. A theme object with palette, typography, spacing and component overrides does not translate into CSS variables and utility classes without decisions. This is most of the work, and it is design work rather than mechanical work, which is why codemods do not help.
Every wrapper you built is now dead weight. Teams using a packaged library accumulate wrappers around its components; in the copied-source model those become an indirection with nothing on the other side, and deleting them is part of the migration.
The honest recommendation
For a small team where the interface is the product: copied source, with the registry landscape as the supply.
For a large team where consistency matters more than distinctiveness: a packaged library, and MUI is a reasonable one.
For an existing MUI application: do not migrate for its own sake. Build new surfaces the other way if you want to, keep the old ones, and never mix the two inside a single screen, where two focus treatments and two spacing scales are visible immediately.
![Calendar [React Day Picker] by originui](https://cdn.21st.dev/cdn-cgi/image/fit=scale-down,width=640,quality=75,format=auto/https://cdn.21st.dev/user_originui/calendar/default/preview.1737991983843.png)
Where else to look
The honest list, because the answer is not always us:
| Source | Best for | Trade-off |
|---|---|---|
| MUI | A versioned API, a theme system and fixes that arrive | Customisation stops where the API does |
| shadcn/ui | Owning the code and changing anything | No version, no upstream fixes |
| Radix / Base UI | Behaviour when the design system is entirely yours | You write every pixel |
| 21st | Components in the copied-source model, with previews | Quality varies by author, so preview before you take it |
Taking one
Every component page has a live preview and the code. Installing goes through the shadcn CLI against our registry:
That key comes from your 21st account, and installs require a membership. Set API_KEY_21ST once in your shell and the command works for anything in the catalogue.
Frequently asked
- What is the real difference between MUI and shadcn/ui?
- Who owns the component code. MUI is a package with a documented API, where fixes arrive with a version bump and customisation stops where the API stops. shadcn copies source into your repository, where you can change anything and nothing arrives on its own, including fixes.
- How hard is migrating from MUI to shadcn?
- Behaviour maps almost one to one, since both rest on similar primitive behaviour. Theming does not map at all: a theme object with palette, typography, spacing and component overrides has to be redecided as CSS variables and utility classes. Every wrapper you built around MUI components also becomes dead weight.
- When is a packaged library the better choice?
- When the team is large enough that consistency has to be enforced rather than agreed, when nobody is being asked to make the product look distinctive, and when you would rather somebody else maintained the combobox. Those are real advantages, not a compromise.
- Can you use MUI and shadcn together?
- Across surfaces, yes, and many teams do while migrating. Inside one screen, no: two focus treatments, two spacing scales and two notions of size are visible immediately, and the fix is always to pick one per surface.