Ricardo Test Setup Install latest Node version Install Docker Compose run docker compose up. This will boot the Postgres database container. Open another terminal Run npm install. Run npm run dev. This start the backend server. You can now make API calls to http://localhost:3001/api/ Endpoints: GET http://localhost:3001/api/accounts/:userEmail POST http://localhost:3001/api/transactions/:userEmail/send POST http://localhost:3001/api/transactions/:userEmail/receive FEATURES: Backend and DB balance validation Row lock to ensure multiple users update the same record correctly DB atomic transaction to avoid transactions/balance issues Avoid ORM to use simple DB connector TODO: Add DB indexes Enable https Enable CI/CD Add logger Use sequelize or other ORM Add security Add periodical balance so we don't need to process all transactions