I Built “Sousa” — a Detective-Style Investigation Board App

You know that board from crime dramas? I made it into an app.

You’ve probably seen it in crime dramas and movies —
a whiteboard covered with suspect photos, evidence, and strings connecting everything together.

I turned that idea into an app.

It’s a digital investigation board where you can place suspects, related people, and evidence on a canvas, then connect them with lines to visualize relationships and organize information.

The app is called “Sousa.”
(It’s pronounced soh-sah, and the name comes from the Japanese word for “investigation.”)

In general, this kind of board is also known as a:

• Investigation Board
• Evidence Board
• Link Analysis Board
• (Sometimes jokingly) Crazy Board

Demo

A live demo is available on GitHub Pages:

https://apu-and-opu.github.io/sousa/

Screenshot

You can freely place:

• Character cards
• Evidence cards
• Notes

Then connect them with arrows and label relationships such as:

• Accomplice
• Witness
• Alibi

Cards are color-coded for clarity:

• Red: Suspects
• Blue: Victims
• Yellow: Related persons
• Green: Witnesses

Features

• Add people, evidence, and notes as cards
• Connect cards with arrows and label relationships
• Attach images
• Save and load data in JSON format
• Supports Japanese and English
• Can be packaged as a desktop app (Tauri) — no installation required

Why I built this

There are already many tools for mind maps and relationship diagrams.

However, surprisingly few are specifically designed as investigation boards, and most of them aren’t very intuitive for that purpose.

So I built a tool with a UI focused on investigation workflows — simple, visual, and easy to use.

I believe it could even be useful as a support tool for real investigations.

Other use cases

This app isn’t limited to detective work. It can also be used for:

• Escape games — preparing puzzle materials
• Writing (novels, scripts) — organizing character relationships and plot
• TRPG / Murder Mystery games — scenario design and session tracking
• Streaming (YouTube / TV) — visualizing relationship maps
• Study / Research — analyzing historical events or complex relationships

…and many other situations.

Tech Stack

Desktop App

You can run it as a web app with npm run dev,
or build it as a desktop app using Tauri.

• Run multiple instances simultaneously (compare different cases)
• Works offline

Download the Windows (.exe) version here:
https://github.com/apu-and-opu/sousa/releases/latest

Note: Windows warning when running the .exe

When running the app on Windows, you may see a warning like:

“Windows protected your PC”

This does not mean the app is unsafe.
It appears because Windows (Microsoft Defender SmartScreen) treats it as an app from an unknown publisher.

This is common for indie-developed applications.

To run the app:

1. Click “More info”
2. Click “Run anyway”

Open Source (OSS)

The project is open source on GitHub:

https://github.com/apu-and-opu/sousa

License: AGPL-3.0

Final thoughts

Investigation boards are a niche tool — but a very useful one.

Whether for real investigations, creative work, games, or research,
I hope this helps anyone who wants to organize complex relationships in a clear and visual way.