Inspiration
Planning group trips is often complicated. Travel plans are scattered across different apps, expenses are difficult to manage, and collecting payments from friends can become frustrating. We wanted to solve this problem by combining AI-powered travel planning with secure digital payments.
What We Built
We built TripLedger AI, an enhanced version of TravelMate that combines a multi-agent AI travel assistant with PayPal's payment infrastructure.
Our application uses four specialized AI agents:
- Flight Agent: Helps users explore flight options.
- Hotel Agent: Provides accommodation recommendations.
- Weather Agent: Retrieves real-time weather information.
- Itinerary Agent: Generates personalized day-by-day travel plans using Google Gemini.
Users can generate travel plans, estimate budgets, save trips, and proceed directly to PayPal Sandbox checkout. The Group Funding Pool feature calculates individual payment shares for group travelers.
How We Built It
We developed the frontend using Streamlit with a custom glassmorphism UI and built the backend using Python and FastAPI.
We integrated Google Gemini for AI-powered itinerary generation, Open-Meteo for weather information, and PayPal REST API v2 for secure order creation and server-side payment capture.
We also implemented JWT authentication, password hashing, idempotency protection, transaction verification, and an auditable transaction ledger using SQLite/PostgreSQL.
Challenges We Faced
Some of our biggest challenges were integrating multiple AI agents, handling external API failures, securing payment operations, and preventing duplicate transactions.
We addressed these challenges through deterministic AI fallbacks, server-side payment verification, idempotency keys, and strict amount and currency validation.
What We Learned
Through this project, we gained practical experience in multi-agent AI systems, API integration, backend security, payment processing, database management, and full-stack development.
Our vision is to make group travel planning smarter, payments safer, and shared expenses easier to manage.
Built With
- css
- fastapi
- google-gemini
- html
- javascript
- jwt-authentication
- multi-agent-ai
- oauth-2.0
- open-meteo-api
- paypal-rest-api
- postgresql
- pydantic
- pytest
- python
- rest-api
- sqlalchemy
- sqlite
- streamlit
- uvicorn
