Sebastian Silbermann
Software Engineer at Self-employed
Berlin, Germany
Summary
🤩
Rockstar
Top expert inWeb Development and JavaScript Ecosystem
Sebastian Silbermann is a software engineer based in Berlin with a decade of experience building and maintaining core React and Next.js infrastructure. As a Next.js contributor and former React core team member, he specializes in UI, rendering compatibility, and TypeScript type safety across major projects like Next.js, React, and DefinitelyTyped. He has driven performance and reliability work in production at Klarna—shipping compiler optimizations that cut app startup by ~30% and creating self-healing CI/CD pipelines. An active open-source maintainer, he’s improved testing tools (Jest, React Testing Library), DOM emulation (jsdom), and package tooling (Yarn Berry), often focusing on last-mile bugs and developer experience. Sebastian blends front-end expertise with full-stack and QA contributions, demonstrating a pragmatic focus on shipping stable, well-typed developer tooling. Notably, he spends as much time refining tests and types as shipping features, making libraries safer for millions of downstream users.
10 years of coding experience
8 years of employment as a software developer
Stackoverflow
3,462reputation
1.1mreached
48answers
3questions
typescript
top-5%
material-ui
top-1%
react-router
top-5%
Github Skills (55)
accessibility10
markdown10
javascript10
accessibilityservice10
testing10
css10
cheat-table10
typescript10
nextjs10
document-generation10
material-ui10
ui-design10
type-definition10
ch10
typedefs10
Programming languages (21)
Github contributions (5)
testing-library/dom-testing-library
Jun 2019 - Dec 2022
🐙 Simple and complete DOM testing utilities that encourage good testing practices.
Role in this project:
Front-end Developer
Front-end DeveloperContributions:244 reviews, 68 commits, 254 PRs in 3 years 6 months
Contributions summary:Sebastian primarily contributed to the `dom-testing-library` repository, focusing on enhancing and refining the library's functionality for testing DOM elements. They fixed various event defaults, added support for pointer events, and improved the `byRole` query, addressing accessibility and performance concerns. Their work involved modifying core files related to event handling, query functionality, and type definitions, aiming to improve the accuracy and efficiency of DOM testing.
testingjavascripte2e-testingdom
testing-library/react-testing-library
Jun 2019 - Dec 2022
🐐 Simple and complete React DOM testing utilities that encourage good testing practices.
Role in this project:Front-end Developer
Front-end DeveloperContributions:97 reviews, 49 commits, 192 PRs in 3 years 6 months
Contributions summary:Sebastian primarily contributed to the testing and enhancement of the React Testing Library for React components. Their work focused on fixing bugs related to event handling, specifically blur/focus events, and ensuring the correct behavior of `baseElement` and the `act` function. They also added tests for the corrected functionalities and refactored cleanup processes to be synchronous and incorporate the `act` function. Furthermore, they implemented and tested new React 18 features.
reactjesttestingjavascriptreact-dom
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