[kreyenborgi]

Bookshop.org lets you filter by drm when you search.

https://www.bloomsbury.com has drm free stuff, and after https://news.ycombinator.com/item?id=42811332 i respect them even more.

Also might be worth scanning old mentions of such https://hn.algolia.com/?dateRange=all&page=0&prefix=true&que...

[tren]

We also do the same at ebooks.com, there's a DRM free section too - https://www.ebooks.com/drm-free

[TeaVMFan]

The bookshop.org filter works nicely. After searching for a keyword, pick "Formats/Ebook/DRM-free". I'll add a link and a note.

[Abishek_Muthian]

libro.fm for DRM free audio books, buying from there supports local book shops.