Shared finances, without the noise. SplitDuo is a self-hosted expense splitting app for small groups — couples, housemates, travel companions, or anyone sharing costs. No subscription, no third-party servers, no data you don't control.
A focused alternative to Splitwise and Cospend, deployable in one docker compose up.
Screenshots
Expense tracking that stays out of your way Add expenses, pick a split, move on. SplitDuo handles the arithmetic — proportional splits, unequal amounts, custom breakdowns — and keeps a live balance so everyone always knows where they stand.
Settlement-aware balances Rather than a raw transaction log, SplitDuo computes net balances across the whole group and surfaces clear settlement suggestions — minimizing the number of transfers needed to settle up.
AI-powered receipt scanning Point your camera at a receipt and SplitDuo prefills the amount, date, and category. Works with any OpenAI-compatible endpoint — bring your own key, keep your data local.
Mobile-first, installable The interface is designed for a phone screen first. Add it to your home screen as a PWA and it behaves like a native app — no app store required.
Invite by email Add your partner via a secure, time-limited invitation link. No account needed on their end until they accept.
Data portability Import existing data from Cospend or a SplitDuo CSV export. Export at any time. No lock-in.
Two-factor authentication Each user can independently enable TOTP-based 2FA on their account.
Fully self-hosted Single Docker container. Your server, your database, your rules.
Requires Docker and Docker Compose.
git clone https://github.com/yourusername/splitduo.git
cd splitduo
docker compose up -dOpen http://localhost:3000 — default login is admin@splitduo.local / changeme123.
Before going to production: set
SD_JWT_SECRET_KEYandSD_INITIAL_USER_PASSWORDto something you control.
Edit docker-compose.yml or pass environment variables directly.
SD_JWT_SECRET_KEY: your-secret-key
SD_INITIAL_USER_EMAIL: admin@splitduo.local
SD_INITIAL_USER_PASSWORD: changeme123SD_DB_HOST: postgres
SD_DB_NAME: splitduo
SD_DB_USERNAME: splitduo
SD_DB_PASSWORD: splitduoSD_BASE_URL: http://localhost:3000
SD_ENVIRONMENT: ProductionAny OpenAI-compatible endpoint works.
SD_AI_BASE_URL: https://api.openai.com
SD_AI_API_KEY: your-api-key
SD_AI_MODEL: gpt-4oRequired for invitation emails and password reset.
SD_EMAIL_SMTP_HOST: localhost
SD_EMAIL_SMTP_PORT: 587
SD_EMAIL_SMTP_USERNAME: ""
SD_EMAIL_SMTP_PASSWORD: ""
SD_EMAIL_SSL: "false"| Layer | Technology |
|---|---|
| Backend | .NET 10, Entity Framework Core |
| Frontend | Vue 3, Nuxt 4, Nuxt UI, TailwindCSS |
| Database | PostgreSQL 17 |
| Deployment | Single Docker container (multi-stage build) |
The frontend is compiled to static files and served directly by the .NET backend — one container, one port, no reverse proxy needed.
cd sd-backend
dotnet restore
dotnet run --project SplitDuo.Api
# → http://localhost:5000cd sd-frontend
pnpm install
pnpm dev
# → http://localhost:3000 (proxies API to :8080)./scripts/dev.sh # Start both
./scripts/dev.sh postgres # PostgreSQL only
./scripts/dev.sh mailpit # Mailpit only
./scripts/dev.sh -d # Drop and recreate volumes firstMailpit (email preview): http://localhost:8025
cd sd-backend
dotnet ef migrations add <MigrationName> --project SplitDuo.Core --startup-project SplitDuo.Api
dotnet ef database update --project SplitDuo.Core --startup-project SplitDuo.ApiBase URL: http://localhost:3000/api/v1
Full spec: OpenAPI YAML
- Project Specification
- System Architecture
- Backend Architecture
- Frontend Architecture
- Database Schema
