Delta Board
A lightweight, privacy-first retrospective tool for teams to collaboratively reflect on their work.
Philosophy
- Lightweight - Minimal dependencies, fast loading, simple architecture
- Minimalist - Two columns: What Went Well and Delta (what to adjust)
- Single Purpose - Built specifically for retrospectives, nothing more
- Privacy Aware - No server-side data storage, all data lives in your browser
How It Works
- Create a board - Generate a unique URL instantly, no signup required
- Share with your team - Send the URL to participants (up to 20 people)
- Collaborate in real-time - Add cards, vote on items, discuss improvements
- Export and close - Download as Markdown when done
Key Features
- Real-time collaboration via WebSockets
- Persistent local storage - Your boards survive browser restarts
- Voting system - Prioritize what matters most
- Card ownership - Edit your own cards, vote on anyone's
- Export to Markdown - Archive your retrospectives
- No accounts - Anonymous, instant access
- Dark theme - Follows OS preference, with manual toggle
- Installable PWA - Works offline, install on any device
Project Structure
delta-board/
├── src/
│ └── DeltaBoard.Server/ # C# server (serves API + static files)
│ ├── wwwroot/ # Client web application
│ │ ├── index.html
│ │ ├── 404.html
│ │ ├── css/
│ │ │ ├── shared.css
│ │ │ └── styles.css
│ │ └── js/
│ │ ├── app.js
│ │ └── theme.js
│ ├── Program.cs
│ ├── BoardHub.cs
│ └── DeltaBoard.Server.csproj
├── tests/
│ ├── DeltaBoard.Server.Tests/ # C# xUnit tests
│ └── client/ # JavaScript Vitest tests
├── docs/
│ ├── DESIGN.md # Technical design documentation
│ ├── LIFE_CYCLE.md # Board phases and transitions
│ ├── PROTOCOL.md # WebSocket protocol specification
│ └── STYLE.md # Visual identity and brand guidelines
├── package.json # JS test tooling
├── vitest.config.js
└── delta-board.sln
Getting Started
Run the Server
cd src/DeltaBoard.Server
dotnet run
The server starts at http://localhost:5123 and serves both the web application and WebSocket API.
Run Tests
# Server tests (C#)
dotnet test
# Client tests (JavaScript)
npm install
npm test
# Browser regression tests (Chromium desktop, mobile, and breakpoint views)
npx playwright install chromium
npm run test:browser
# Cross-browser behavior checks
npx playwright install firefox webkit
npm run test:browser:cross
The browser suite starts the ASP.NET application, exercises multi-participant workflows,
checks accessibility and offline behavior, and compares reviewed visual baselines.
Linux CI is the authority for visual comparisons; macOS runs skip screenshot assertions.
To create candidate Linux baselines after the workflow is available on the default
branch, run:
gh workflow run ci.yml --ref <branch> -f update_snapshots=true
Download and review the visual-baselines-linux artifact before committing changed
images. Run npm run test:browser:update directly only in a matching Linux environment.
When bootstrapping the workflow before dispatch is available on the default branch, the
first pull-request run stores missing Linux snapshots in the browser-failure artifact.
Run with Docker
# Build the image
docker build -t delta-board .
# Run it
docker run -p 8080:8080 delta-board
The server starts at http://localhost:8080. The container listens on port 8080 by default (configurable via ASPNETCORE_HTTP_PORTS).
CI
GitHub Actions runs on every push to main and on pull requests:
- Build the .NET server
- Run .NET server tests (xUnit)
- Run JavaScript client tests (Vitest)
Releases
When a GitHub release is published, a workflow builds a multi-platform Docker image (linux/amd64, linux/arm64) and pushes it to GHCR.
| Release type | Example tag | Container tags |
|---|
| Pre-release | v0.1.0-preview.1 | 0.1.0-preview.1 |
| Stable | v1.0.0 | 1.0.0, latest |
# Pull and run a specific version
docker run -p 8080:8080 ghcr.io/yoannchaudet/delta-board:1.0.0
Documentation
License
MIT
