fread.ink is a free as in freedom alternate operating system for electronic paper ebook readers.
fread is currently under development and not yet ready for normal use.
April 4th 2020: This project is on hold while the main developer is helping scale up Covid-19 diagnostics.
March 2nd 2020: I am currently working on the fread UI which is based on WebKit2GTK. This includes a work-in-progress ebook reader application. We decided to go with a modern web rendering engine since the most-used reflowable ebook formats are HTML+CSS (with some extensions). The other option would be the Cool Reader engine which definitely has a much smaller memory footprint but is developed mostly by a single person, which doesn't bode well for its future (or current) support for something as complicated as modern HTML+CSS.
Status is: Currently you need a 5th generation non-touch Kindle device with root access to try things out. Graphics is working. Button input is working. USB networking is working. WiFi needs a bit more work. USB storage device mode is not yet working. Power button not yet working. Making an installer that doesn't require jailbreaking is in progress. Development of UI and initial ebook reader app is in progress.
July 25th 2018: Looks like juul's talk got a writeup on hackaday.com. Nice!
July 22th 2018: juul gave a talk about the project at HOPE 2018 which you can download in webm (VP9) format here (642 MB). Unfortunately several fascist and white nationalist intimidators and harassers showed up at HOPE and the organizers did almost nothing to prevent this. The fread.ink project fully supports the statement released by several attendee organizations and individuals.
The plan is to support the most popular e-readers with electronic paper displays starting with i.MX5 and i.MX6 devices, which surprisingly covers most of the widely sold models including all Kindles since the 4th generation (2011), every Kobo since the Kobo touch (2011) and the latest Nooks (since 2016). The older Kobos and Kindles that use older i.MX chipsets will likely be supported at some point. For older Nooks we haven't sufficiently investigated the available source code to know whether support is feasible.
We're working on an image that can be used to flash non-rooted devices, erasing the original operating system. To learn how to flash the system without rooting start here. This will be turned into a simple one-click cross-platform installer.