Maybe not be exactly what you're looking for, but Logseq has a daily note-taking function. When you open it for the first time of the day, it shows you a blank journal with the current date as the header and you can put whatever you want in it. It has a search function that can search through all the notes you've made for specific text. It saves each day as a separate markdown file and you can sync these to your phone or other devices with Syncthing, a cloud service like Google Drive, or with git if you host something like Forgejo.

The only thing about Logseq is that it doesn't use the standard syntax for Markdown checkboxes. Instead, it has it's own Todo syntax, which is perfectly human readable without Logseq, but loses out of some convenience if you were to migrate to something else.

If you wanna go nuts on the data, probably Obsidian.md with the built-in Daily Note plugin and the Dataview plugin, which allows you to do all kinds of crazy operations on the data in your vault as if it was a database.

If you wanna go less nuts, obsidian still has tagging, linking notes, daily notes, and all kinds of other stuff built-in and is extensible by things like the Calendar plugin from the community.

And everything is stored as plain Markdown with the occasional hint of JSON (for some plugins) so you're not locked into using Obsidian until the end of time. Your data is yours.

(I realise this sounds like an ad but I've just been using Obsidian for years now and I enjoy it)

If it isn't meant for others to see, what's wrong with a .txt file you just add notes to?

I like:

https://github.com/usememos/memos

Here is a list of note-taking apps:

https://github.com/tehtbl/awesome-note-taking

By the way, I am building my own Journaling system, it's still early stages and I am looking for ideas!

I took a look at the awesome self-hosted repo and found DailyTxt. I have no experience with it but maybe worth a try?

Plain text or org mode file.

I dont have the same usecase, but BookStack will check most of your boxes

Joplin

Obsidian is great for note taking and creating pathological atomic notes that connect to each other

Why not use Journal from Silverbullet since you already have it https://silverbullet.md/Library/Journal

You can just copy those templates and edit them as you wish, for example I have one for Stand-ups at work

WordPress could probably do it, you don't have to give it public access.

You have and use Silverbullet. Why not use templates and Silverbullet? It’s basically made for exactly that use case.

tiddlywiki?

Joplin

Like a blog?

Check out Wordpress, Hugo or Ghost.

I personally use private github repo as my diary. I don't want to lose my data by accident. I trust github more than I trust myself

I use Standard Notes

Memos is a great app for this or if you want it local, use DiaryVault

DiaryVault can sync (encrypted) with Nextcloud too. Memos is a serverapp, it has a good responsive webapp

I think OP needs to explain why a note taking app is not a diary app in their view.

Would Obsidian work for you? The notes are stored locally, and the software uses markup for formatting and stuff. You can get it synced to your phone with Dropbox, OneDrive, etc.

I use Orgzly Revived with Syncthing, it's pretty good

Notesnook doesn't have self hosting yet (the developers are working on it) but it might be a good option in the future.

Org roam could work if you’re your cool with emacs. Create files on the fly that are named with the date/topic and it could be setup to allow timestamps since you mentioned that. Notes can be linked to each other or easily merge or split as it develops.

Also org roam comes coupled with a daily diary that attaches to emacs calendar system.