Joplin - an open source note taking and to-do application with synchronisation capabilities for Windows, macOS, Linux, Android and iOS.
Joplin is fairly popular.
A local-first, non-linear, outliner notebook for organizing and sharing your personal knowledge base. Use it to organize your todo list, to write your journals, or to record your unique life.
Logseq, it has a journal function and it's really helpful for consolidating all of your knowledge on topics. Check out the guides for it
Appwrite - The Open Source Firebase alternative introduces iOS support . Appwrite is an open source backend server that helps you build native iOS applications much faster with realtime APIs for authentication, databases, files storage, cloud functions and much more!
Build your personal knowledge base with Trilium Notes
Trilium has been great in my experience for writing down notes and as a general knowledge book.
Notes app recommedation
2 projects | reddit.com/r/fossdroid | 23 Jan 2022
An opensource clossplatform note-taking app?
2 projects | reddit.com/r/opensource | 19 Jan 2022
Anyone knows an app that has sub-pages and outline features?
3 projects | reddit.com/r/opensource | 18 Jan 2022
Text editor similar to Word or Google Docs for Obsidian?
3 projects | reddit.com/r/ObsidianMD | 26 Jun 2022
Looking for a self-hosted todo list app
1 project | reddit.com/r/selfhosted | 26 Jun 2022