NotePub is described as 'is the best online notepad, and it's free. Notes can be public or private and can include pictures, files, links, tags, and encrypted data. You decide who gets to see your notes, and who can edit your notes' and is an website in the Office & Productivity category. There are more than 100 alternatives to NotePub, not only websites but also apps for a variety of platforms, including Windows, Mac, Android and Linux. The best alternative is Joplin, which is both free and Open Source. Other great sites and apps similar to NotePub are Standard Notes (Freemium, Open Source), Microsoft OneNote (Freemium), Evernote (Freemium) and Simplenote (Free, Open Source).
NixNote, formerly Nevernote, is an open source client for Evernote . It is written in Java so it will also run on Windows & OS-X, but the primary focus has been to try and get a usable environment for Linux.
myBase is a unique free-form database software that allows entry of unstructured text, webpages, images, documents, emails and even arbitrary files without regard to length or format. All information is automatically compressed and stored in the tree structured outline form.
A simplified, RedNotebook-type journal/diary app. With a focus on minimal design and a distraction free writing environment. Makes a folder full of dated text files that are easy to access even without the journal program.
Tracks is a web-based application to help you implement David Allen’s Getting Things Done™ methodology. It was built using Ruby on Rails, and comes with a built-in webserver (WEBrick), so that you can run it on your own computer if you like.