Tripper

Track, split, and settle expenses with friends, family, or colleagues during your trips. No more awkward money conversations.

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🚀 Tripper – Project Story

🌟 Inspiration

We’ve all been in that situation after a fun trip — when the real challenge begins: splitting expenses. Who owes whom? How much? And why are there so many transactions?

Existing apps don’t make it easier either:

  • They’re cluttered with ads
  • They have limits on trips/expenses
  • And they often create confusion instead of solving it

At one point, I simply couldn’t tolerate ads anymore — so I decided to build Tripper, a clean, ad-free, and optimized expense manager for trips.

💡 What it does

  • A trip creator sets up a trip and invites friends via personalized email links.
  • Friends join by verifying through the link.
  • Participants can log their expenses throughout the trip.
  • At the end, an optimized settlement algorithm calculates the minimum number of transactions needed.
  • Every participant automatically receives a personalized PDF report with all expenses and their share.
  • Integrated Voice AI with ElevenLabs → users can log or query expenses hands-free with natural speech, making it more convenient while traveling.

Designed mobile-first — because during trips, people use phones, not laptops.

🛠️ How we built it

  • Frontend → React.js (responsive, mobile-first)
  • Backend & Auth → Firebase (authentication, Firestore for data storage, and email invites)
  • Database → Firebase Firestore
  • Invitations → Personalized secure email links generated via Firebase functions
  • Voice AI → ElevenLabs for speech-to-text and natural voice interaction, enabling users to add expenses or get trip summaries hands-free
  • Algorithm → Graph-based settlement optimization

Example Calculation

Suppose three friends spend:

  • ( A = 200 )
  • ( B = 300 )
  • ( C = 500 )

Total = ( 200 + 300 + 500 = 1000 ).
Each person’s fair share =
[ \frac{1000}{3} \approx 333.33 ]

Net balances:

  • ( A = 200 - 333.33 = -133.33 ) (owes 133.33)
  • ( B = 300 - 333.33 = -33.33 ) (owes 33.33)
  • ( C = 500 - 333.33 = +166.67 ) (is owed 166.67)

Optimized settlement:

  • ( A \rightarrow C: 133.33 )
  • ( B \rightarrow C: 33.33 )

✅ Just 2 transactions instead of multiple messy ones.

🚧 Challenges we ran into

  1. Designing an optimal settlement algorithm (early versions caused redundant payments).
  2. Integrating Firebase authentication with smooth onboarding while keeping it secure.
  3. Handling real-time expense updates with Firestore sync across users.
  4. Implementing Voice AI with ElevenLabs so that commands feel natural and responsive.
  5. Formatting PDF reports in a clean and readable way for all users.

🏆 Accomplishments that we're proud of

  • Built a fully functional, ad-free expense manager tailored for trips.
  • Integrated voice commands using ElevenLabs to make expense logging effortless.
  • Leveraged Firebase for secure authentication, real-time collaboration, and scalability.
  • Created an optimized settlement system that reduces transactions.
  • Automated personalized PDF reports sent via email.

📚 What we learned

  • How to combine Firebase’s real-time database with collaborative features.
  • Leveraging voice AI (ElevenLabs) to enhance UX beyond traditional inputs.
  • Graph-based optimization for real-world financial settlements.
  • Importance of mobile-first, ad-free design in real-world usability.

🔮 What’s next for Tripper

  • Payment Integration → Direct UPI/PayPal settlements within the app.
  • Multi-trip Dashboards → Manage several trips simultaneously.
  • Offline Support → Log expenses offline, sync later when online.
  • AI Insights → Personalized spending breakdowns and smarter settlement suggestions.
  • More Voice Features → Richer natural language understanding for expense queries like “Who owes the most?” or “How much did I spend on food?”.

✅ With Tripper, trips end with memories, not money headaches.

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