With roughly two million downloads per months, there must be a lot of big and small companies using this package. Please share your success stories!
If you would consider providing long term support through donations that would be great! Open collective or Paypal (please mention immer in the comments both cases)
@mweststrate Firstly I want to say huge thanks for your library. The writing of redux reducers is much easier and faster with immer ๐คค
A little bit about us:

There's a few projects at Google using immer in Angular + ngrx apps (I'm working on one of them). I can't remember which ones are publicly launched, but if you're curious I can look into it some more.

AWS is using immer in services.
I am using immer for redux. That's cool. Thank you very much.
https://github.com/fwh1990/redux-model-ts
Our product is in development and when we release it then I will send details. By the way I like it.
At Quizlet we've adopted Immer as a replacement for ImmutableJS. Main reasons were that we kept running up against static typing problems and that it seems to be unmaintained.

https://logodix.com/logo/717774.png
400K+ LoC in TypeScript frontend
At Staffmatch weโre working on a new redesigned app where immerjs is heavily used both for redux and useState. I have no words to express how awesome it is, how it eases working with any state and optimizations. Complex table - easy; dropdown, date picker to work smoothly in IE11 - not a problem. So thank you a lot for making such a beauty!
At Course Hero we have started to use Immer on new React apps, where it is helping us simplify updates to complex state objects and increase the maintainability of the codebase.

Volvo Group Connected Solutions uses Immer in all our major React+Redux projects, for example https://volvoconnect.com
https://www.coxautoinc.com/ we are using in our digital retailing apps.
At lusha.co we are using Immer in most of our projects :)

React Native Boilerplate is using immer :)
https://github.com/keremcubuk/react-native-boilerplate
Amazon uses it!
Redux docs now appear to recommend immer โ https://redux.js.org/tutorials/essentials/part-2-app-structure
Appcircle.io uses immerjs
Hello! Thanks for the awesome library!
ImaWakatta - learn Japanese the fun and interactive way

Small team (Myself as the dev and a few content authors). Code wise I would say medium? We moved from Redux to Immer + hooks, which greatly simplified everything.
https://imawakatta.com/ (soft launched, still working out some kinks)
We're using Immer to build Worksphere.co, a workplace management platform for safe offices and flexible teams.
Product๏ผWorkplace Management for a Safe Return to Office
Company: worksphere.co
Screenshot:

at cylus we are using immer to solve complex state updates.

Most helpful comment
Redux docs now appear to recommend
immerโ https://redux.js.org/tutorials/essentials/part-2-app-structure