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Zim Desktop Wiki: https://zim-wiki.org/
It's good for creating interconnected articles on your desktop. No mobile version though, so it's more of a knowledge base that a notes app.
Attachments and links to external files work beautifully. WYSIWYG editor, all articles stores as plain text files with zim wiki syntax, attachments are plain files in folders
Technically OneNote online in office 365 is also an option
Btw no built in sync, but since it's all just plain files in folders syncing works beautifully with Own loud/Nextcloud
There is built-in git versioning though, though I'm not sure when you'd use that for personal use
I'd try anytype too, it's a lot of stuff and almost out of beta. It seems pretty good
Zettlr.
Logseq is my go to. It can be as simple or complex as you want, and it's open source under AGPL 3.0 which is really important to me.
Creating a TiddlyWiki is also an alternative. Especially to Obsidian
Create a folder, put markdown files in it, sync* and backup* the folder however you like and edit the files with whatever you like*.
Within my folder I have a daily journal - start each day with a list of what I hope to achieve today and make notes throughout the day as I progress on those tasks. The next day that journal becomes something I'lll refer back to in the morning to decide what to do next. Depending on the project - weekly or monthly might be more suitable than daily. Or maybe something else entirely.
I also have folders an files for longer term tasks.
If you want to collaborate, make a second folder and choose a sync platform you can all agree on.
(* I use GitHub for Sync, Backblaze B2 for backup, and Visual Studio Code for editing, with extensions for markdown and making GitHub a little easier... specifically GitDoc for auto-commit/push/pull and Markdown All in One for formatting/etc. Also Copilot is handy for some note taking tasks. The "foam" extension mentioned here looks like it might be great too)
Not a great direct alternative, but rnote is pretty good
I’ve tried about everything and landed on Workflowy and love it. Simple, fast, excellent for organizing.
If you're looking for touch/stylus compatibility I highly recommend the Excalidraw plugin for Obsidian.
If you are looking for a handwritten notes app that syncs across devices you could give Saber a try.
I use qownnotes in combination with nextcloud. Supports mark down, git like history and syncing with the nextcloud notes app, which you can also use on your phone.
I dunno if this is weird or what but personally I can't stand markdown editors. It's 2023 and Microsoft Word is a fairly polished thing that I expect replicated in some way in my note taking app.
Currently I'm using Notion and it's pretty nice. Free for students too which is great.
I was using Wiki.js which was nice but a bit clunky and I ran into a few showstopper bugs that I couldn't bother fixing.