Not for everyone, but I use a self-hosted single user email server for this. All the formatting your client permits, clients for every platform, attachments, organization into folders, synced automatically everywhere, etc. No spam filtering, MARC, DKIM, and the like because you only ever email yourself and you don’t permit external senders. I love it.

How about AnyType? It matches your requirements.

Obsidian and good ol’ paper and pen. (or epaper). The paper I use is on bullet jpurnal style.

code editors might have the features you want, and its easy to repurpose a code editor into a notes app.

sync a folder between your devices (syncthing is great for this) and put markdown text files in it. I like to call this folder “Memo” since its like writing letters to myself.

edit the markdown using VS Code (desktop) or Carbon (android). I haven’t tested whether Carbon can do this, but I know in VS Code, you can reorder a list with keyboard shortcuts.

click anywhere on a line of text, then hold Alt and press Up arrow, and the text will swap places with the line above it.

edit: Syncthing and Carbon are open source. VS Code has some proprietary code added by Microsoft, but none of it is relevant to your use case, so you may prefer the fork called Codium.

Joplin and Obsidian.

Hi quaff!

The app I use for this purpose is called Notally, on android. It supports reordering the checkboxes, but it doesn’t do find in page or sync to web (although it can do backup /restore – I sync the folder with nextcloud and I can access the text files)

That said if you try it, you might love how simple it is and use it for something!

https://f-droid.org/packages/com.omgodse.notally

I use Workflowy. Partner and I replaced G Keep with it. It can do A and maybe C.

I self-host Notesnook and found it easy to set up. Been using it as my main note-taking app for years now and I’m really happy with it.

Triliumnext can do everything you want. Its pretty damn powerful

Others have mentioned Syncthing as a sync solution. I’d like to add a couple points:

Syncthing can work fine even for solutions that are intended to use their own sync, provided it’s a single-user setup. You’re not likely to make simultaneous changes on 2 devices, so collisions are unlikely.

Also for using Syncthing, I recommend Syncthing-Fork for Android - it moves sync conditions into the folder/job rather than global. Very useful when you have jobs you want always syncing, and jobs you want to only sync on wifi and power.

If using iOS there’s an ST client called Möbius Sync ($5), developed by a company the financially supports Syncthing.

For Windows, get SyncTrayzor - it makes running and managing ST easier.

I use Logseq with ToDoList plugin to handle task list. Logseq is similar to obsidian but open-source. And to syncronize notes among devices, I use syncthing. No need to selfhost.

Notesnook. And if you like it, buy the pro ASAP since they’re raising the prices this week.

I use Tasks.org with caldav (Radicale) on android and thunderbird on pc, would that work?

https://play.google.com/store/apps/details?id=org.tasks

I see tasks.org supports etesync, which encrypts data. I have never used it though

Docmost?

I spent several years looking for the perfect selfhosted solution to this, but ultimately I realized an offline solution was just going to be better. So I started using Obsidian which is as simple or complex as you want with no paywall.

Some of the self hosted solutions I’ve tried were:

• Memos
• Blinko