CycleSpend

Inspiration

We were inspired by research showing that spending behavior and impulse control can fluctuate across the menstrual cycle. Many women experience predictable changes in energy, mood, and self-regulation, yet personal finance tools treat spending as uniform over time. This disconnect can make budgeting feel frustrating or ineffective. We wanted to explore how acknowledging menstrual cycles could lead to more realistic and supportive financial planning.

What it does

CycleSpend is a finance app that helps users understand how their spending patterns change across menstrual cycle phases. It maps transaction data to cycle days, visualizes phase-based spending trends, and helps users plan budgets around those patterns. Instead of labeling certain spending as “bad,” the app anticipates higher-spend phases and encourages proactive planning through adaptive budgets, savings buffers, and cycle-level insights.

How we built it

We built a React frontend with Tailwind CSS to focus on clarity and visualization. Firebase handles authentication and data storage, while transaction data is simulated using the Capital One Nessie API. Cycle phases are calculated client-side based on user input, and spending data is analyzed by phase rather than by calendar month. We used Google Gemini to generate monthly cycle reports that summarize trends and suggest adjustments for future cycles.

Challenges we ran into

One big challenge was turning menstrual cycle research into real features that actually work for different users without making too many assumptions. Getting the phase-based budget to feel flexible and not pushy took a lot of trial and error. Plus, we had to make sure the visuals clearly showed spending patterns, especially since we only had a short time to demo everything.

Accomplishments that we're proud of

We’re proud of building a functional prototype that connects menstrual cycle tracking with financial data in a meaningful way. The cycle-spending heatmap and phase-based budget allocation clearly demonstrate the core idea. We’re also proud that the project reframes overspending as a predictable pattern rather than a personal failure.

What we learned

We learned that spending habits aren’t random, they’re highly contextual, and the menstrual cycle can have a real impact on decision-making. On the technical side, we got hands-on experience working with financial APIs, managing user data, and using AI to generate personalized insights. This project also showed us how important it is to design tools around how people actually behave, not how we expect them to.

What's next for CycleSpend

Next, we want to test with more users and real bank data to make budgets smarter and more personal. We’ll improve how the app learns from multiple cycles and builds better symptom-spending links. Privacy is a big focus too. We’re also planning a premium version with extra features like detailed AI reports and subscription alerts. In the future, we want CycleSpend to be the go-to app for budgeting based on your cycle.