GreenPulse

Inspiration

Transportation is one of the largest contributors to carbon emissions, yet most people don’t see the impact of their daily choices. While fitness and finance apps successfully motivate behavior through tracking and rewards, sustainability lacks that same feedback loop. GreenPulse was inspired by the idea of making eco-friendly choices visible, measurable, and rewarding — turning small daily actions into meaningful impact.

What it does

GreenPulse is a mobile app that automatically tracks your trips and rewards sustainable transportation. It detects whether you’re walking, biking, or using public transit, calculates the CO₂ you save, and converts that into points. Users can redeem points for real rewards like products, discounts, and experiences. The app also features sustainable business check-ins and a scoring system to promote eco-friendly local businesses.

How we built it

We built GreenPulse using React Native, Expo SDK 55, and TypeScript for a fast, cross-platform mobile experience. GPS tracking was implemented with expo-location, while local data is stored using AsyncStorage. We designed a trip detection system based on movement and stop duration, and used speed thresholds to classify transportation modes. A lightweight verification system using image capture and hashing was added for transit and business check-ins. The app is structured with reusable components and file-based routing using Expo Router.

Challenges we ran into

One of the biggest challenges was accurately detecting transportation modes using only GPS and speed data, especially distinguishing between biking, driving, and public transit. We also faced issues with false trip detection due to GPS noise and small movements. Designing a verification system without a backend AI model required creative solutions. Additionally, balancing automation with a smooth user experience — making the app effortless but still reliable — was a constant challenge.

Accomplishments that we're proud of

We’re proud of building a fully functional, end-to-end mobile app that works automatically without requiring user input. The seamless trip tracking, CO₂ calculation, and rewards system come together into a cohesive experience. We also successfully combined sustainability with gamification, creating a system that not only tracks behavior but actively encourages change.

What we learned

We learned how to work with real-time location data and handle its inconsistencies. We gained experience designing systems that infer user behavior from limited inputs. On the development side, we improved our skills in React Native, Expo, and TypeScript, as well as structuring scalable and maintainable codebases. We also learned the importance of user motivation and how design decisions can influence behavior.

What's next for GreenPulse

Next, we plan to improve the accuracy of transportation detection using machine learning and expand the verification system with more advanced image analysis. We also want to introduce a backend to enable cloud sync, leaderboards, and social features. Expanding partnerships with real businesses and offering more meaningful rewards will be key to increasing user engagement and real-world impact.

Built With

• claude
• cursor
• expo.io
• reactnative
• typescript