Though not always a very active one, I'm a core contributor to React Query, mainly when it comes to server rendering support and hydration.
Besides having written the server rendering tests, I haven't contributed much code to Redux, but I have been pretty involved in all kinds of issues and discussions around server rendering, hydration and code splitting.
Rollup by default removes directives like 'use client' during the build. I made a plugin to preserve them so libraries using Rollup, like React Query, can support React Server Components.
This was my first attempt at a asynchronous React server side renderer with support for Suspense (shortly after Suspense was announced). It was implemented as a custom renderer on top of the regular React reconciler, usually used for client renderers.
This was the successor to Aldrin and my second attempt at implementing asynchronous SSR. Aldrin was slow, had some tradeoffs, edge cases and weirdness so for this attempt I forked React and implemented the asynchronous parts directly into the official renderer instead which worked pretty well.
PriceRunner is a shopping comparison service available in the UK, Sweden and Denmark that was recently aquired by Klarna and is now also available in the US at klarna.com/us/shopping. I mainly worked on the frontend platform which was built on top of a custom server side setup with built in support for nested routes with co-located data fetching (think Remix) and a lot of other good stuff. Performance, SEO and internationalization were big focus areas.
SVT is the Swedish Public Service Television Company, where I mainly worked on the news site. SVT migrated to React early so we built our own framework on top with a lot of bespoke functionality, especially focused on accessibility and making sure the entire page also worked without JS (try it!).