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

Apu & Opu — Sat, 18 Apr 2026 08:25:16 +0000

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

Technology	Purpose
React	Frontend framework
Vite	Build tool
React Flow (@xyflow/react)	Canvas, nodes, and connections
Tailwind CSS	Styling
Tauri	Desktop app packaging

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:

Click “More info”
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.

DEV Community: Apu & Opu