I Reorganized 1000 Notes in 30 Minutes with Johnny Decimal

February 22, 2026 · 6 min read · obsidianjohnny-decimalproductivityorganizationai

My Obsidian vault had turned into a junk drawer.

There were 201 markdown files in the root, with every new note landing beside all the old ones. Kubernetes.md, Einbürgerung.md, and Money Printer.md were sitting next to each other as if this was a reasonable way to live.

My macOS Documents folder was in the same state. Some folders had numbers. Some had names from old projects. Some were clearly created during a moment of false optimism and then abandoned forever.

This is how personal knowledge systems rot: a hundred small “I’ll clean this up later” moments.

I finally cleaned it up. It took about 30 minutes.

Why Johnny Decimal

I had known about Johnny Decimal for a while. The idea is simple: split your stuff into ten areas, then ten categories inside each area.

Something like this:

10-19  Personal & Admin
20-29  Learning & Knowledge
40-49  Work
50-59  Property & Big Life
60-69  Family
70-79  Tools & Setup
80-89  Creative Inputs
90-99  Creative Outputs

The numbers are useful, but the real value is the constraint.

You get ten areas and ten categories per area. That blocks the usual escape routes: Misc, Archive, Stuff, and my personal favourite, New Folder. When something refuses to fit, I have to stop and decide what it actually is.

That thinking is the whole point.

The mess before

My Obsidian vault already had a few Johnny Decimal-ish folders:

40 Billie
60 Family
80 Creative Inputs

But the root was still full of loose files. Two hundred and one of them.

That usually means one thing: the system has lost trust. If I trusted the structure, I would file notes immediately. Instead I was creating notes in the root because every filing decision required a tiny bit of energy.

The Documents folder had the same problem in a different form. There was 10 Money, 30 Health, 89 Creative Inputs, and random old project folders like Datomic, Puzko, and hodur. Some of these I probably had not opened in months.

Search still worked, of course. Search always works until it doesn’t. Finding one file was fine. Understanding what I had was the problem.

The structure I ended up with

I settled on eight areas:

10-19  Personal & Admin     finance, health, home, German life, daily notes
20-29  Learning & Knowledge languages, DevOps, AI, architecture, books
40-49  Work                 Billie, IT-Premium, side projects
50-59  Property & Big Life  apartment, car, big purchases
60-69  Family               family notes and documents
70-79  Tools & Setup        editors, CLI tools, self-hosted, home infra
80-89  Creative Inputs      clippings, videos, social, RSS
90-99  Creative Outputs     blog, LinkedIn, talks, ideas

I deliberately left 30-39 empty.

At first I had 31 Health, but health is a category in my life rather than a whole area. It belongs under 12 Health & Wellbeing inside Personal. Johnny Decimal is good at exposing this kind of over-design. When a category is pretending to be an area, the numbering makes it obvious.

Where AI helped

This is the part that would have been painful by hand.

I asked my AI assistant to read the filenames, propose categories, and separate the obvious from the ambiguous. It moved the boring 95% into place and gave me a short list of files that needed human judgment.

That is the right division of labour. I want the agent to sort 201 filenames, propose a structure, and write the shell script. I still make the decisions about meaning.

The result:

201 files -> 29 Johnny Decimal folders
0 files left in the vault root

Then we did the same thing for Documents on macOS:

renamed existing folders to match the new system
moved stray files into proper categories
put loose attachments into 00 Attachments
kept Obsidian and Documents using the same numbers

That last bit matters. 11 Finance & Legal means the same thing everywhere now. Tax notes live in Obsidian 11; scanned tax documents live in Documents 11. Boring. Predictable. Good.

What made it stick

Moving files is easy. Keeping the system alive is the hard part.

So I added three small things.

First, a master index: 00.00 Index.md. It lists every area and category, with a one-line description of what belongs there.

Second, area notes like 10-19 Personal & Admin.md. These link to the category folders and contain filing rules. For example: web clippings go to 81, even if I learned something from them.

Third, the same numbers across places. Obsidian and Documents now agree, which removes a surprising amount of friction.

A filing system only works if the next action is obvious. If I have to stop and debate the philosophy of a PDF, the system has already failed.

The annoying details

A few things broke, or at least needed cleanup.

Area folders should not contain files. I had files directly inside 80 Creative Inputs and 90 Creative Outputs. In Johnny Decimal, area folders are conceptual. Files go into categories like 81 Clippings or 91 Blog Posts & Drafts. Once I moved those files down one level, the structure felt much cleaner.

Some notes already had Johnny Decimal-style names, like 81.22 CSS Flexbox.md, but lived in the wrong parent folder. The filename was right; the location was wrong. Easy fix, but worth checking.

Daily notes needed to become part of the system. I had a separate Daily/ folder, because of course I did. I renamed it to 16 Daily Notes and updated the automation that creates them.

And yes, automation broke. I had cron jobs and scripts referencing old paths like ~/Obsidian/Daily/. If your notes are wired into scripts, agents, or cron jobs, grep for old paths before you declare victory.

Was it worth it?

Yes.

Folder aesthetics are a trap. The value is that I no longer have to think about where a new note goes.

If I read something useful, it goes into 80-89 Creative Inputs. If I write something, 90-99 Creative Outputs. German bureaucracy, 10-19 Personal & Admin. Work, 40-49.

Simple rules beat clever systems.

Johnny Decimal also gave me a useful map of my life. Looking at the area list, I could see what was missing, what was overgrown, and what I was pretending was important. That might be more valuable than the cleanup itself.

If you have 50 notes, maybe do nothing. Search is fine.

If you have hundreds of notes, documents, PDFs, drafts, project files, and automations growing around them, impose a structure before the mess becomes infrastructure.

Johnny Decimal is not magic. It gives you just enough constraint to make decisions.

That was exactly what I needed.