looking for open source e book reader

I know that I read a series of posts about open source e readers, and which ones work. I did not need one then. Maybe the conversation happened in the threads about the Better World book?

My searches have not found what I am looking for.

My devices are android and windows 10.

Are you looking something like this:

https://play.google.com/store/apps/details?id=org.readera&hl=en_US&gl=US

Or this might help:

https://www.androidauthority.com/best-ebook-ereader-apps-for-android-170696/

Or maybe this is what you were looking for though this is a cbook:

https://permies.com/t/cbook

Or this:

https://permies.com/wiki/40/112519/Building-World-Backyard-angry-bad#1065898

Edit:

   Lyda Eagle wrote:
   If anyone is looking for An APP, there is a free one for windows.

   freda epub ebook reader

Thanks for the recommendation, Lyda. This opens the file![/quote

For Android, I really like muPDF Mini. It is open source, and the full version is also available for Windows, although I have not tried it on there.

There's also this: Calibre. It's available for Windows, Mac, and Linux (not for any mobile device, however). Also, it isn't just a thing for which to read ebooks, it can manage your device's library and you can use it to convert files from one format to another. If anyone self-publishes, it can assist with that (convert your book from whatever format you've written it into a suitable format for Kindle, etc.)

It is also extensible: there's a boatload of extensions you can add on to it. My favorite is 'Search the Internet,' a plugin that enables you to search all types of online databases out there for that one book you know is out there somewhere....

Paul Sofranko wrote:There's also this: Calibre. It's available for Windows, Mac, and Linux (not for any mobile device, however). Also, it isn't just a thing for which to read ebooks, it can manage your device's library and you can use it to convert files from one format to another. If anyone self-publishes, it can assist with that (convert your book from whatever format you've written it into a suitable format for Kindle, etc.)

It is also extensible: there's a boatload of extensions you can add on to it. My favorite is 'Search the Internet,' a plugin that enables you to search all types of online databases out there for that one book you know is out there somewhere....

I forgot to mention that aside from using it to download books from wherever, you can also download wiki pages (by means of some addons.)  You can also download from specific sites, such as fan-fiction and recipe sites.

Thanks everyone! Now I'm off look at features to decide.