I used to have notes everywhere. Google Docs for work stuff, Apple Notes for random thoughts, Notion for projects I never finished, and a graveyard of markdown files scattered across folders named things like "misc" and "to-sort-later." Finding anything meant searching three apps and hoping I remembered which one I'd used.
A couple years ago I moved everything into Obsidian. Having it all in one place helped, but I still ended up with the same chaos. A flat pile of files with no structure. I'd create a note, name it something reasonable, and then never find it again because I couldn't remember if I'd called it "Jordan trip" or "2024 travel plans" or just "vacation."
Then I found Johnny Decimal.
Why Most Systems Fail
Most organization systems fail because they're too flexible. You can create unlimited folders, nest them however you want, and name them whatever makes sense in the moment. Six months later, nothing makes sense. You have "Work" and "Professional" and "Career" all holding different things. "Travel" nested inside "Personal" nested inside "Life," or maybe it's just floating at the root level next to "2023 stuff."
Johnny Decimal forces constraints. You get exactly 10 areas of life (numbered 00-09 through 90-99). Within each area, you get 10 categories. That's it. 100 total buckets for everything you'll ever need to organize.
When I first read that, I thought there's no way 100 categories is enough. Seemed almost insulting. Then I tried to list out everything I actually care about. Turns out most of my "organization" was just different names for the same handful of things.
My Actual Structure
Here's what my vault looks like:
00-09 System/
├── 00 System Management
├── 01 Daily Notes
└── 02 Research
10-19 Tech/
├── 11 Code
├── 12 Homelab
├── 13 Projects
├── 14 Internet & Websites
└── 15 AI
20-29 Travel/
├── 21 Perks & Discounts
├── 22 Trips
└── 23 Travel Resources
30-39 Personal/
├── 31 Career
├── 32 Finance
├── 33 Living
├── 34 Health & Style
├── 35 Entertainment
├── 36 Food
├── 37 Personal Development
├── 38 Speeches & Writing
└── 39 Content
00-09 System is for meta stuff. The notes about notes. My inbox where quick captures land before I sort them. Templates. Daily notes. Research projects that don't fit anywhere else yet. It's the junk drawer, but a structured one.
10-19 Tech covers my technical life. Code references I look up repeatedly. Homelab documentation. Active projects. AI prompts and tools. Anything that would feel at home on a developer's desk.
20-29 Travel holds more than you'd think. I have a folder for each trip with research, booking info, and trip reports after. Another folder for loyalty programs and perks. One for packing lists and general resources. When I'm planning a trip to Jordan, I know exactly where to look. When I get back, I know where to put the notes.
30-39 Personal is the catch-all for life. Career stuff like resumes and interview prep. Finance with tax documents and account info. Living arrangements. Health records. Entertainment like reading lists and things to watch. Food and recipes. Personal development. Writing projects. Content ideas.
That's it. Four areas. I don't use 40-99. Maybe I never will. The system doesn't care if you leave gaps.
Why It Actually Works
Not the numbers themselves. The constraint.
When I save a note about Turkish baths in Petra, I don't wonder where it goes. It goes in 20-29 Travel, then 22.01 Trips, then Jordan. That's the only place it could go. The path is obvious before I even create the file.
When I'm looking for my brother's wedding speech, I don't search. I navigate to 30-39 Personal, then 38.01 Speeches & Writing. There it is.
The numbers create a physical address for every piece of information. 32.01 means something. It's Finance within Personal, and the .01 means it's a specific document or subfolder. When someone asks me where I keep tax documents, I can say "32.01 Finance, Tax Documents folder." Precise in a way that "somewhere in my notes" never was.
Look back at my structure. Pretend it's yours. Your building just sent you something about your rental agreement changing and you want to save it. Where does it go?
It's personal. So 30-39 Personal. It's about living arrangements. So 33 Living. Maybe a file like rental_agreement_2026.pdf.
You could go a level deeper: 33.01 Living/10 Yearly Rentals/2026/<file>.pdf. But you get the idea. I can organize within the drawers whenever I want. The drawers just help me put things in a state where they can be organized.
Another one: you find a cool recipe online and want to save it. Personal, so 30-39 Personal. Food, so 36 Food. Done. Maybe later you organize 36 Food into subfolders for cuisines or meal types. Maybe you never do. Either way, you know where recipes live.
Daily Notes and Quick Capture
Most of my interaction with Obsidian is through daily notes. Each morning a new file appears in 00-09 System / 01.01 Daily Notes, named with today's date. I use a template that creates the same structure every time:
# 2025-01-03
## Tasks
- [ ] Review PR for auth refactor
- [ ] Update API docs for v2 endpoints
- [x] Fix flaky integration test
- [ ] Schedule 1:1 with manager
## Notes
That's it. Two sections. Tasks for things I need to do today. Notes for anything else that comes up.
Throughout the day, I dump thoughts in the Notes section. Random ideas, things to look up later, links someone sent me. At the end of the day or week, I move anything worth keeping to its proper home. The rental agreement reminder goes to 33.01 Living. The recipe link goes to 36.01 Food. Most things just get deleted.
Capture fast, sort later. The daily note is ephemeral. Most of what goes in there doesn't need to live forever. But when something does, I know where it belongs.
How Trips Work
Travel planning used to overwhelm me. Research scattered across browser tabs and random notes. Booking confirmations buried in email. Itineraries… somewhere.
Now each trip gets its own folder under 22.01 Trips. Before I go, it fills up with research. Restaurant recommendations. Things to see. Logistics like visa requirements and local emergency contacts. Booking numbers and hotel addresses.
After I get back, I write a trip report. Not a polished travel blog, just practical notes. What I actually did each day. What worked and what didn't. Prices. Recommendations. The stuff I wish I'd known before going.
My Jordan trip report has notes like "Uber from airport is 30 JOD to downtown" and "don't wash your face in the Dead Sea, the salt will wreck your eyes" and "the monastery hike from Little Petra takes a couple hours and you descend 9000+ steps at the end." A year later, when a friend asks about Jordan, I can just send them the file.
The Stuff That Doesn't Fit
Some things resist categorization. Research projects that span multiple areas. Ideas that aren't developed enough to place. Things I'm actively thinking about but haven't decided what they are yet.
These go in the System area. 02.01 Research for deep dives. The inbox for quick captures. Daily notes for transient thoughts. The structure has room for ambiguity, which I didn't expect going in.
I still occasionally create a note and realize a week later it's in the wrong spot. Or I'll debate whether something is "Career" or "Personal Development" for way too long. The system doesn't eliminate decision fatigue entirely. It just makes most decisions obvious.
Getting Started
This is just my take on the system. My organization works for me, but yours will look different. The general idea is about shelves and drawers: thinking of everything in terms of where it physically lives, not what it's related to or when you created it.
If you want to start thinking about it for yourself, the Saving Files page on the Johnny Decimal site is a good place to begin.
Don't try to replicate someone else's system exactly. My four areas reflect my life. Yours might need five or six. Maybe you don't travel much but you have three hobbies that each deserve their own area.
The point isn't the specific numbers. It's the constraint. Pick your areas, keep it under ten. Pick your categories within each, keep those under ten per area. Then stop reorganizing and start using it.
I spent years tweaking systems instead of writing in them. Johnny Decimal gave me a structure boring enough that I stopped thinking about it. That's the whole trick.