Spines is described as 'set of powerful tools that will improve your learning experience and help you obtain more knowledge with less friction in three simple steps:' and is an app in the Education & Reference category. There are more than 100 alternatives to Spines for a variety of platforms, including Windows, iPhone, Android, Mac and Online / Web-based. The best alternative is Joplin, which is both free and Open Source. Other great apps like Spines are Standard Notes (Freemium, Open Source), Google Keep (Free), Microsoft OneNote (Freemium) and Evernote (Freemium).
Joplin is a free, open source note taking and to-do application, which can handle a large number of notes organised into notebooks. The notes are searchable, can be copied, tagged and modified either from the applications directly or from your own text editor.