Expenses Tracker

Inspiration

Managing personal finances is something that many people struggle to maintain consistency with. Existing budgeting apps are often bloated, expensive, or store your data in opaque ways. I wanted to build something simple, fast, and secure that puts the user in control, with real-time insights and a frictionless UI.

So I created Expenses Tracker — a modern, serverless expense tracker that helps users stay on top of their budgets and spending without compromising speed, scalability, or simplicity.

What it does

Expenses Tracker helps users track daily expenses, organise them into budgets, and visualise where their money goes. Users can log expenses, set budgets, view spending summaries, duplicate past entries, and search across categories — all within a fast, mobile-friendly UI.

How we built it

Frontend:

Built with React, TypeScript, Tailwind CSS, and Vite
Uses React Context for state sharing
Authenticated with AWS Cognito
Features: search (Fuse.js), duplication, and real-time budget tracking

Backend:

Provisioned using AWS CDK (TypeScript)
API Gateway (with Cognito authorizer + throttling + logging)
Lambda functions for expenses, budgets, and users
DynamoDB with GSI for querying by category/user
Logs sent to CloudWatch with managed IAM roles and proper CfnAccount configuration

Challenges we ran into

CloudWatch log role registration: API Gateway failed deployment until CfnAccount and IAM role dependencies were resolved
DynamoDB modelling: Designing a schema that supports both budget-bound and standalone expenses with flexible querying
Token expiration and 401s: Properly handling expired tokens in the frontend while showing meaningful errors
Route conflicts: Avoiding ambiguity in API Gateway routes like /expenses/{id} vs. budgets/{id}/expenses/${id}