Base Web
Uber's React design system, built on an overrides API.
Base Web is Uber's React design system, built around an override pattern that was genuinely ahead of its time: every component exposes its internal sub-components for replacement, so you can swap a piece of a dropdown's internals without forking the component.
At a glance
| Install | npm install baseui styletron-react styletron-engine-atomic |
| Styling | Styletron, an atomic CSS-in-JS engine |
| Signature | the overrides API, deep component customisation |
| Licence | MIT |
| MCP server | not published |
| Last GitHub release | June 2023 |
Check the maintenance situation first
That last line matters more than anything else on this page. The most recent tagged release on GitHub is dated June 2023, more than three years ago. There is no official deprecation notice, and packages may still move through npm on a different cadence, but a public release timeline that quiet is a signal you should verify before adopting.
We list it because the ideas in it are still worth knowing and because a lot of production software runs on it. We are not recommending it for a new project in 2026 without checking the state of the repository yourself.
The overrides pattern is worth studying regardless
Every Base Web component accepts an overrides prop keyed by internal part, letting you replace styles, props or the component itself at any level of the tree. Radix later solved a similar problem with asChild, PrimeVue with pass-through props. Base Web got there first.
Choose it if
- You have an existing Base Web codebase and want the reference documentation.
- You want to understand where deep component customisation patterns came from.
Look elsewhere if
- You are starting something new. Verify the maintenance status before you commit.
- You do not want Styletron. It is a hard dependency, not an option.
