Splitfool

Open source alternative to Splitwise backed by AWS Lambda

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Inspiration

Most expense-splitting apps are bloated: they ask for logins, require everyone to download an app, and lock data behind accounts. SplitFool was built as a minimalist, open-source alternative. Simple, accountless group management using short codes, with a clean web UI and deploy-anywhere backend. The vision: group splitting that works like a shared whiteboard, not a social network.

What it does

SplitFool is a full-stack web app that lets users track and simplify group expenses without accounts, emails, or integrations. Key features:

  • Groups are created and joined using 6-character codes, no login required
  • Anyone with the code can add/remove expenses and members
  • Automatically calculates net balances and optimal payments

How we built it

SplitFool is built with a modern, minimal stack:

  • Frontend: Svelte, TypeScript, Vite, Tailwind CSS hosted on Cloudflare
  • Backend/API: Hono framework with ElectroDB and DynamoDB (single-table design), deployed via AWS Lambda
  • Dev containers: Docker for local development and hot reload
  • Infra tooling: Terraform

Challenges we ran into

  • Designing a truly stateless user experience, without logins or sessions, that’s still secure and collaborative
  • Implementing full local development parity with AWS services (like simulating DynamoDB locally with Docker)
  • Balancing minimalist UI with enough clarity for users to track and settle expenses in multi-user flows

Accomplishments that we’re proud of

  • Fully functional MVP without requiring any user data
  • Clean separation of concerns between frontend, backend, and infra for both dev and prod environments
  • Designed from day one for scalability via serverless AWS

What we learned

  • Serverless can be lean if you build with the right primitives (e.g., ElectroDB + Lambda)
  • Svelte remains unmatched for fast, expressive UIs with minimal overhead
  • Even in 2025, most “simple” apps aren’t actually simple — minimalism takes discipline

What’s next for SplitFool

Build a Gemini-powered chat interface that allows users to control expenses using natural language, including:

  • Adding expenses via receipts, screenshots, or chat messages
  • Parsing group chat screenshots to auto-import members
  • Running rebalancing and summaries conversationally
  • Integrating Gemini 2.5 Flash for fast multimodal parsing
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