Why you need a single source of truth for your PKM system

Having a single source of truth for all types of data in your PKM is key to a solid system

Why you need a single source of truth for your PKM system

In this article, I explain what a single source of truth is and discuss why you need one for your personal knowledge management system.

This content is part of my Obsidian Starter Kit

What is a single source of truth

A Single Source of Truth (SSOT) is a central location where you aggregate data or metadata about specific information.

The idea is to have one reliable source to go to when you need to find something. If you have a single source of truth for your pictures, then you only need to check there to find what you need.

The two possibilities are:

  • The single source of truth contains all the data
  • The single source of truth acts as a reliable index to all the data. For instance, if you have pictures stored on a NAS, on Google Photos, on different offline hard disk, etc then the single source of truth might be a wiki page where you list where each part of your collection is stored

Combining both is actually the best approach. You have a central storage location for the information, and if you forget about it or someone else needs to find something, then it's still possible to use the index to quickly find the information.

A single source of truth makes it easy to locate what you are looking for (i.e., helps with findability)

Why you need a single source of truth for everything

In a Personal Knowledge Management (PKM) system, having a single source of truth for each type of information and each project is of the utmost importance. A single source of truth is where you can go to either find all the information or to find where what you are looking for is located.

When there are multiple input sources for a certain type of information, it’s critical to decide where you want to store the information. It may be okay to store it at multiple locations (either with or without duplicates), but you need to have a single source of truth.

Once you have created a single source of truth, then everything becomes easier: easier to locate, easier to backup, easier to migrate, easier to use, easier to explain.

Single source of truth example

Let’s take an example: family pictures. You take pictures with your phone, maybe your partner takes with his or hers. Maybe those pictures are automatically synchronized with Google Photo or iCloud. Maybe you have a camera and SD cards filled with old photos. Maybe you store those on your computer or on a NAS. Friends take pictures of you. Just with this example, you see how quickly we can create a mess for yourselves if we’re not careful. It is true for family pictures, but also for many other types of data.

Continuing with the family pictures example, you certainly want to store them all in a single location, and then make sure to backup everything. Photos from your phone should go there. Pictures from your partner’s phone should go there. Photos from your camera should go there. Images that were received from friends as well. You get the point. In my case, the single source of truth for family pictures is my NAS. Every single picture we take ultimately goes in there. When I need to find one, I don’t have to think twice about where to start looking. If I lose my phone, I generally won’t be worried about lost pictures.

Information types that benefit from having a single source of truth

As I’ve mentioned, having a single source of truth is useful for all kinds of information.

Here are some examples:

  • Articles and books
  • Bookmarks
  • Contacts
  • Documents
  • Hardware
  • Ideas
  • Pictures
  • Inspiration: articles, books, expressions, quotes, videos, etc.
  • Knowledge
  • Notes
  • Personal goals and plans
  • Project plans and details
  • Software
  • Tasks
  • Videos
  • etc.


Here are some recommendations:

  • Define a single source of truth for each type of data
  • Create and maintain an index of what is where for each type of data (i.e., create a single source of truth about your single sources of truth!)
  • Regularly review your index to make sure it still reflects the reality

More generally, make sure you actually design your Personal Knowledge Management system.

How the Obsidian Starter Kit helps

The Obsidian Starter Kit I've created provides a clear folder structure to centralize and organize the following types of information:

  • Articles and books
  • Contacts
  • Ideas
  • Inspiration
  • Knowledge
  • Notes
  • Personal goals and plans
  • Project plans and details
  • Tasks
  • and more (up to you)

The main benefit of centralizing all of this information in a single tool is that it makes it possible to link everything together and reuse content easily without duplicating it needlessly.

Linking helps you create a strong private Web of knowledge. You might work on a specific project with one of your contacts. You can then take your meeting notes and link those with your contact and with your project, giving you various ways to look at the information.

In addition, you can also use the Obsidian vault to act as the single source of truth for the rest of your PKM system. You can create notes to document all sorts of things:

  • List all the places where you store your hardware
  • Document the inventory of the things you own; when/where you bought each, etc
  • List your favorite movies, TV shows, and ratings
  • List what you’ve lent to friends
  • List what you store in the attic
  • etc

Of course, it’s up to you to decide whether to use the proposed structure or only a part of it. There are no rules!

Again, this makes it much easier to find things later on. No need to think much: go to your single source of truth to find out where what you’re looking for is located.

Going further

If you want to further explore Personal Knowledge Management, then take a look at starter kit for Obsidian. It will give you a solid starting point for your note-making efforts.

Also check out my Personal Knowledge Management Library. It’s a huge collection of resources (articles, books, videos, YouTube channels, and a lot more).

By the way, I publish a weekly newsletter about PKM, note-taking, lifelong learning, and more!

If you find PKM interesting (I really hope you do!), then you might want to join our community.


In this article, I've explained the idea of a single source of truth and why it's so useful. This concept applies to PKM, but also to many other domains (e.g., software development, documentation, data management, accounting, law, etc).

Keeping this concept in mind will help you avoid ending up duplicating information, forgetting where you put X or Y, and whether this version or that version is the right one.

That's it for today! ✨

About Sébastien

Hello everyone! I'm Sébastien Dubois. I'm an author, founder, and CTO. I write books and articles about software development & IT, personal knowledge management, personal organization, and productivity. I also craft lovely digital products 🚀

If you've enjoyed this article and want to read more like this, then become a subscriber, check out my Obsidian Starter Kit, the PKM Library and my collection of books about software development 🔥.

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If you want to discuss, then don't hesitate to join the Personal Knowledge Management community or the Software Crafters community.