Tinynotebook is described as 'Simple, Yet powerful notesystem created with using the best editors of the web. PHP, MariaDB' and is a Note-taking Tool in the Office & Productivity category. There are more than 100 alternatives to Tinynotebook for a variety of platforms, including Windows, Mac, Android, iPhone and Online / Web-based. The best alternative is Joplin. It's not free, so if you're looking for a free alternative, you could try Standard Notes or Google Keep. Other great apps like Tinynotebook are Microsoft OneNote (Freemium), Evernote (Freemium), Simplenote (Free, Open Source) and CherryTree (Free, Open Source).
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.