I know there are a lot of project management apps out there, but is there a simple one you could recommend for a small-scale personal project? It's mainly meant to keep myself organized, and to break down tasks.

https://plane.so/

But mostly because I can self-host

If you only need a Kanban board, Vikunja is pretty great

Came here to recommend exactly this!

Though the wonderful thing about plane specifically is you don't have to selfhost it. Its great without self hosting too.

I've done project management with small team and solo projects for around 5 years now and I've seen a lot go into the shitter... Plane is open-core, and I expect it'll be safe for a long while given the way other project management software has been going.

I've used Trello the most, but also lots of Jira and HackNPlan. Taiga (there are two, forget which is which off top of my head) was alright until it wasn't. I started REALLY looking after this, and landed on either Wekan or Plane. If you can selfhost and don't mind the limited featureset (possibly fine solo!) - wekan may be great. But plane is absolutely wonderful and what I use with my tiny team now.

I like this:
https://www.theideon.com/

And if you are ok with something not open source but still selfhostable and need "jira but for developers": there is youtrack, which you can find a docker img for somewhere (or you can use their cloud). It phones home to check the license and is free for up to 10 users. It's very capable and feature rich.

I don't know exactly what you're after since project management is such a broad topic, but I can just say how I do this.

I keep 2 obsidian vaults: 1 personal and 1 professional. Among hundreds of other notes and topics I keep a project note per project (some personal some professional), keyed by project directory. Each keeps a running history of what is happening with each project. Then my daily journal links to the projects I'm working on with short notes about what is happening.

This is an aside, but obsidian.nvim is a superb way to interact with these notes.

If you're looking for kanban and such, that's a completely different approach, but I find after decades of sucking at keeping track, this has finally fit nicely with how I approach projects.

I’m using https://kanban.rs/ right now. I just wish the data was stored in a way that was a bit more resistant to git conflicts.

Cryptpad has kanban board as well

Good shout. I do much the same - in fact /just/ created a step by step markdown list to replace a shower pump in my home.

No good for bigger projects, gantts etc, but for small stuff it's ideal. Also means you've got a permanent and portable archive that's easily searchable.

I tried different things over the years and each time I simply forget to update the tool and just keep track of what needs to be done in my head. In my experience those things are useful for organizing teams. For a one person project a piece of paper should be enough.

I like Siyuan. You can write notes, then right click on a line of text, and tell it to add to a database table. Then you can edit on the database table (reword it or mark it as complete) and then it will sync back to your notes as well that it's complete. You can also add columns to the table if you want to categorise the task, and filter to see what is important (your P1s only for example) It's also open source and encrypted. And there is a mobile and linux app.

Another good one is Quire.

I use a whiteboard for the main overview and cocktail napkins taped to the wall for current activities and ongoing updates. Pert and Gannt have fallen by the wayside but it has small amounts of agility. /s

I've wondered about this too! I came to like Jira at work and at some point I tried setting that up for myself but turned out many of the actually useful features like time tracking were paid features, so I very quickly gave up on it.

i feel this -- i'm in that weird state where it's technically 3 of us, but neither my manager nor the undergraduate new hire really touch it anywhere near as much as i do so the burden of keeping track is higher than it needs to be and i sometimes don't bother to update it as a result. (they don't even notice when i don't).

I don't know which OS you want this tool to run on, if you want/need a remote access, or the level of details you need for your tasks, but - since nobody mentioned it so far - I'd recommend giving Taskwarrior a look.
You can also complement it with Timewarrior.

Same here, though I’d be suprised if there wasn’t a plugin for Obsidian which would provide Gantt charts, Kanban, etc.

I use Obsidian for documentation and such Vikunja for task management (Kanban).

If you already have nextcloud, it has a decks feature