PKM Systems Compared: Which Personal Knowledge Management System Should You Use?
A PKM system (personal knowledge management system) is how you capture, organize, and retrieve information. The right system depends on how you think, what you work on, and how much complexity you're willing to manage.
This guide compares the main frameworks — PARA, Zettelkasten, Johnny Decimal, and tags-only — without judgment or cult-of-productivity hype.
First: what is a PKM system?
A PKM system is a set of habits and tools for managing the information you encounter. It has three parts:
- Capture — Saving information before you lose it (web clipping, quick notes)
- Organize — Structuring it so it's retrievable
- Use — Actually finding and acting on what you've saved
The "system" part is the structure you apply to steps 2 and 3. Different frameworks propose different structures.
Important: The best PKM system is the one you actually use. A theoretically perfect system you abandon after two weeks is worse than an imperfect one you maintain for years.
Framework 1: PARA (Projects, Areas, Resources, Archive)
Created by: Tiago Forte (Building a Second Brain)
Structure: Every piece of information belongs in one of four categories:
- Projects — Work with an active goal and deadline
- Areas — Ongoing responsibilities without an end date (health, finances, a job role)
- Resources — Topics you're interested in but don't have an active use for yet
- Archive — Completed projects and inactive material
How it works in practice:
When you capture a web clip, ask: is this for an active project? → Projects folder. Is it ongoing reference for a role? → Areas. Is it a topic you care about generally? → Resources.
When a project completes, move the folder to Archive.
Strengths:
- Action-oriented. Everything is connected to something you're doing or might do.
- Simple enough to maintain. Four folders, not thirty.
- Works with any tool (Notion, Obsidian, Evernote, Google Drive, paper).
Weaknesses:
- The line between Areas and Resources is often blurry.
- Not ideal for connecting ideas across projects.
- Doesn't encourage synthesis or linking between notes.
Best for: Knowledge workers who think in projects — consultants, managers, freelancers, product managers.
Framework 2: Zettelkasten
Created by: Niklas Luhmann (sociologist, 20th century)
Structure: Atomic notes, each on a single idea, connected by links. No folder hierarchy. Notes are discovered by traversing links, not by navigating folders.
How it works in practice:
Each note gets a unique identifier (traditionally a number, now often a timestamp). Notes link to other notes. Over time, you build a web of connected ideas — the "slip box" (Zettelkasten means "slip box" in German).
When you read something interesting, you:
- Write a short note capturing the idea in your own words
- Link it to related notes
- The web grows over time
Strengths:
- Surfaces unexpected connections between ideas
- Encourages genuine synthesis (you have to put it in your own words)
- Scales beautifully — the value compounds over time
- Produced Luhmann's 70+ books and 400 academic papers
Weaknesses:
- Slow to set up. High up-front cost per note.
- Not action-oriented — hard to use for project management.
- Requires discipline to maintain atomic notes (one idea per note).
- Tools like Obsidian make this easier, but it's still a significant methodology.
Best for: Writers, researchers, academics, and anyone whose primary output is ideas — papers, articles, books, deep analysis.
Framework 3: Johnny Decimal
Created by: Johnny Noble
Structure: A strict numeric taxonomy. The world is divided into 10 Areas (00–90). Each Area has up to 10 Categories. Each Category has up to 10 items. Every piece of information gets a unique ID like "22.04".
How it works in practice:
You design your decimal system upfront. Categories might look like:
10 Finance
11 Tax
12 Investments
20 Work
21 Projects
22 Reference
Then you file everything with its ID. The ID makes retrieval deterministic — you always know where to look.
Strengths:
- Highly organized. Zero ambiguity about where things go.
- Works across every tool and file system.
- Great for people who like rigid structure.
Weaknesses:
- High setup cost — you need to design your taxonomy before you start.
- Doesn't adapt well as your work changes.
- Encourages filing over connecting. Ideas don't link to each other.
Best for: People who love systems, hate ambiguity, and have stable, well-defined domains of work.
Framework 4: Tags only (no folders)
Structure: No folders at all. Every note gets one or more tags. Discovery is through search and tag filtering.
How it works: Capture → tag → search. That's it.
Strengths:
- Zero setup. Start immediately.
- Flexible — items can have multiple tags without duplicating.
- Search-centric, which is how most people actually retrieve information.
Weaknesses:
- Tags proliferate. After a few months you have 200 tags that mean slightly different things.
- No hierarchy — hard to see the shape of your knowledge.
- Doesn't scale beyond a few thousand items without discipline.
Best for: People who resist formal systems and work better with flexible search. Good starting point before you decide you need more structure.
Comparison table
| Framework | Structure | Best for | Complexity | Tool requirement |
|---|---|---|---|---|
| PARA | 4 folders | Project-oriented workers | Low | Any |
| Zettelkasten | Linked atomic notes | Writers, researchers | High | Obsidian, Roam, Logseq |
| Johnny Decimal | Numeric hierarchy | Systematic thinkers | Medium | Any file system |
| Tags only | No folders | Beginners, flexible thinkers | Very low | Any |
What about the web capture layer?
All four frameworks need a web capture layer. This is the tool that saves web pages into your system, regardless of which organizational framework you use.
PageStash integrates with any PKM framework:
- PARA users: Use PageStash folders that mirror your PARA structure. Clips go into Projects, Areas, or Resources.
- Zettelkasten users: Export clips as Markdown → import into Obsidian → write a Zettel linking to the clip.
- Johnny Decimal users: Tag clips with your decimal IDs.
- Tags-only users: Tag clips in PageStash directly — the same tags you use elsewhere.
The web is the primary source of research for most knowledge workers. PageStash ensures web sources are captured with full fidelity (text, screenshot, HTML) and searchable. Free to start.
The recommendation
Start with PARA if you don't have a system yet. It's the most immediately useful for project-based work and requires the least upfront setup.
Move to Zettelkasten if your work is primarily writing or analysis and you want to invest in building a knowledge base that compounds over years.
Use tags only if you're starting fresh and don't want to commit to a framework before you understand your needs.
Johnny Decimal is for people who already know they love systems and can design their taxonomy upfront.
Most effective knowledge workers end up with a hybrid: PARA folders for projects + a Zettelkasten area for permanent notes + tags for quick classification.
FAQ
What is the difference between PARA and Zettelkasten? PARA organizes by project and action — where are you using this? Zettelkasten organizes by idea and connection — how does this relate to what I already know? PARA is optimized for execution. Zettelkasten is optimized for insight.
Can I use PARA and Zettelkasten together? Yes. Many researchers use PARA for project files and active work, with a Zettelkasten "slip box" area inside Resources for permanent notes. Tiago Forte's own system evolved this way.
Do I need Obsidian for Zettelkasten? No, but it helps. Obsidian's bidirectional linking, graph view, and local-first storage make it the most natural fit. You can implement Zettelkasten in Roam Research, Logseq, or even a paper box — but Obsidian has the best combination of features and cost (free for local use).
