I love how 90% of replies are recommending software that isn’t open-source.

I was about to suggest obsidian+syncthing when I saw your edit. I’m using the same combo on multiple devices and it’s working flawlessly.

Obsidian is great, and I agree the sync is too much. It does work flawlessly but Im going to try Syncthing again after my one year is up.

Another newcomer that is promising is Acreom. Doesnt require an account on PC. Currently does on mobile though. But like Obsidian, it is a pile of markdown files. No weird database silliness like Joplin does.

I use TiddlyWiki via TiddlyPWA. It’s an offline-capable PWA with a very quick sync capability. It works beautifully on my phone and desktop. It doesn’t have folders, but it does have nestable tags, which works really well for me. I don’t think it supports markdown out of the box, but I’m positive you can find a plugin for it. Plugins are crazy simple to install; you just drag and drop a link into you wiki tab and confirm installation.

Joplin with any of the dozen or so sync services it supports out of the box.

IMO, FOSS doesn’t do well with cross platform note taking and task tracking. I find it best to have two separate, but complimentary, workflows for mobile and desktop note taking.

My mobile notes are things like door combinations or pill counts/dosages/spellings, or travel info for longer/complex trips. Things I need at hand and that I can check quickly. I just use the default android app. Or very often just a piece of paper.

I use org roam with git for my computers. These are mostly code snippets, articles, journaling, etc. Things that are involved to the point I would rather wait for a keyboard than work on them with a phone. Same is true for writing on a desk rather than a pad.

I do have a few ways to go between devices:

• I can read my computer notes on gitlab if needed
• I use Signal Note to Self to keep or send one offs and images. (SUPER handy!)
• Firefox syncs tabs

Probably a few others, but I don’t take pictures of my computer screen because I’m not an animal.

My workflows are pretty orthogonal, so this works well for me. Your mileage may vary.

I highly recommend:

• Web: Nextcloud + Nextcloud Notes App + Qownnotes Sync App
• Desktop: Qownnotes and/or vim (or any texteditor of choice)
• Mobile: Nextcloud Notes

Main advantage of this software stack over other solutions like joplin is the handling of the notes. Everthing is stored in a simple folder structure in plain markdown text files (*.md). This means if anything breaks, you are always able to read and edit with any text editor on any system! I switched away from joplin because it stores the notes in a database and notes file names are a cryptic string, so if you are not able to load joplin it’s very hard to find anything.

Sync Obsidian with Syncthing.

I like Notesnook, although it’s a bit expensive.

Because of a different Lemmy post, I’m just now trying out Orgzly. It looks terrific so far, and I think it meets all your needs. It stores everything in plain text, so you just have to sync the text files.

edit: as noptys points out, Orgzly Revived is what you want to use (and what I meant to recommend).

anytype.io

Joplin with Syncthing works well for me.

I actually use Obsidian on my Linux desktop, synced with Syncthing to my Android phone, iPad, home server, etc (have version control also active to keep older copies of notes). Mainly because the volume of notes I do is on the desktop, and I need them for reference everywhere. But I’m not sure Obsidian is best as a phone app (bit busy), but you could test it with a simple UI.

Logseq could be another option although I’m unsure about syncing, syncing might be possible via NextCloud/syncthing

Using Obsidian with mega on desktop and FolderSync covering syncing the android side of it. Works fine.