Obsidian is a fantastic note-taking app, and it's easy to assume that you can only use it for super-serious professional things. But let's be real, here; we D&D DMs need all the organization we can get to keep our brains in check and our campaigns running smoothly. Trust me, there have been countless times where my players brought up a character and location, and I just stared at them and said "...who or where was that, again?"
Fortunately, we have the power of a productivity powerhouse to organise our imaginary games of fantasy better. So, here are some ways I use Obsidian to prep my D&D games.
Essential for random place names and die rolls
So there's this really cool addon called the Solo RPG Toolkit. It's not developed or endorsed by Obsidian, but it is a good add-on for anyone who wants to use the note-taking app for their D&D games. In fact, this add-on was what got me thinking about using Obsidian as a D&D assistant in the first place.
As the name suggests, the Solo RPG Toolkit was designed with systems where you play by yourself in mind. It may seem very difficult to play an RPG by yourself, but there are plenty of games out there where the system acts as the game's master, and you figure out what's happening with dice rolls and randomisation tools.
However, these tools are just as useful for playing and planning a D&D campaign yourself. You can generate place names and NPC titles, figure out motives and goals, and even roll the dice. I like using the probability calculator to solve in-world conflicts; for example, if the party spares a bandit who goes back to their camp to tell their leader, what are the odds they'll be believed and/or spared? I then set the probability based on feelings and let the engine decide for me.
I discussed my experience with this addon in my piece about the Solo RPG Toolkit on Obsidian, so check it out if you'd like to know more.
2 Using Obsidian's tools to get all my notes in one place
It's like a second brain
So the cool thing about Obsidian is that it's not just an app where you take notes and that's it. You can connect the notes within a web and interlink between them to make navigation super easy.
To do this, I create a new note, then title it with whatever I want to write in the note. Sometimes I write about the next stage in the party's quest, sometimes it's an NPC, and sometimes it's a location or objective. Now, every time I refer to that note's title in another note using double square brackets, the notes connect to one another. I can now click on those links and get taken to the entry's page to edit or use the material I had prepared earlier.
I also really enjoy using the "daily note" option. When you make a daily note, Obsidian automatically creates one with the current date as the title. If you already have a daily note going, clicking the create button takes you to it. There, you can type whatever's on your mind for the day. I love using this feature as a quick "brain dump," where I have a sudden burst of inspiration but I don't have the time or the energy to sift through my notes, I just put it all into the daily note and then sift through it later.

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1 Navigating your notes while in-game is a breeze on mobile
Better than PDFs, in my opinion

Source: mockup.photos
When I run a D&D game, I like using a digital medium to store all of the campaign details. I know some DMs love printed sheets, but I like the customization and ease of use you get when you go digital. Case in point: if you put your D&D notes on your phone or tablet, your entire campaign is ready to go in a flash.
Because of the note linking system, you can easily flick between each character, quest, or location description by tapping their name in the text. Navigating between your notes is super quick, so you can bring up whatever NPC, item, or trap the players just encountered in a moment's notice. I've tried running a game using a PDF before, and scrolling through the pages to find what you want is a chore; on the other hand, Obsidian makes things super easy to navigate.
Obsidian is more than a D&D tool, but I love it nonetheless
If you want to get into the nitty-gritty, learning about how Obsidian works and how you can use it to organise your notes can really help your productivity. However, it's also great as-is as a D&D planner. Give Obsidian a shot and see how you like it.