This tiny app allows you to take short notes in your Kindle’s Web Browser. Typing can be laggy due to the e-ink display.
The text will be saved in local storage, so don’t worry about closing the browser or refreshing the page.
You can download the note as a text file, and then it will appear in your Kindle Library. Afterwards, when you connect your Kindle by USB, you can transfer the files.
Alternatively, you could simply take a picture of the note with your phone, and then select the text if your phone supports it.
The app is a single file and open source. It only stores data locally, it does not send any data anywhere.