Tasan

This project was bootstrapped with create-ts-node.

Tasan is a full-stack web application for splitting bills and tracking shared expenses.

The repository is a TypeScript monorepo built with pnpm workspaces. The web application uses React Router, React, and Tailwind CSS; data is stored in DynamoDB; and the production infrastructure is defined with AWS CDK.

Tasan is under active development. Interfaces, deployment configuration, and data models may change without notice before a stable release.

• Node.js and pnpm versions specified in .tool-versions
• Docker, for running DynamoDB locally
• AWS CLI, for creating the local DynamoDB table and working with AWS infrastructure

Install the workspace dependencies:

pnpm install

Create the web application's local environment file:

cp packages/web/example.env packages/web/.env

Start DynamoDB Local and create the application table:

docker compose up -d dynamodb-local
./scripts/create-local-table.sh

Start the TypeScript workspace watcher in one terminal:

pnpm dev

Start the web development server in another terminal:

pnpm --filter @tasan/web dev

The application is available at http://localhost:5173.

The example environment uses the deployed Cognito user pool for authentication. Update the authentication variables in packages/web/.env if you need to use a different provider or client.

• @tasan/common: shared domain utilities, validation, currency handling, graph operations, IDs, and tracing.
• @tasan/data: DynamoDB access and persistence models.
• @tasan/web: the full-stack React Router web application.
• @tasan/infra: AWS CDK stacks and runtime entry points.
• @tasan/export: utility for exporting split data.
• @tasan/benchmark: Lambda benchmark utility.

Run these commands from the repository root:

• pnpm build — build all workspace packages.
• pnpm dev — watch and compile the TypeScript project references. Run the web development server separately.
• pnpm test — run package tests plus formatting, linting, and type checks.
• pnpm test:format — check formatting.
• pnpm test:lint — run ESLint.
• pnpm test:types — type-check all project references.
• pnpm fix — apply ESLint and Prettier fixes across the repository.
• pnpm clean — remove generated workspace output.

To run a command for one package, use a pnpm filter. For example:

pnpm --filter @tasan/web test

Infrastructure is managed from packages/infra. See the infrastructure README for AWS authentication and CDK commands. Deployments modify live AWS resources and should only be run intentionally.

Contributions are welcome. Read CONTRIBUTING.md before opening a pull request and follow the Code of Conduct when participating.

Please do not report security vulnerabilities in a public issue. Follow the private reporting process in SECURITY.md.

Copyright © 2026 Santeri Hiltunen.

Tasan is licensed under the GNU Affero General Public License, version 3 or later. If you modify Tasan and make it available to users over a network, the AGPL requires you to offer those users the corresponding source code.