Full-Stack Developer for Financial Calculator Web App + API Integrations

Job Details

Description

Summary I’m building a mobile-first financial decision web app for U.S. military members. The first tool helps a servicemember determine whether buying or renting at a duty station is financially stronger based on their specific situation. Important: This is not a project starting from scratch. I already have: A completed and validated Excel financial model that serves as the calculation source of truth An approved mobile UX prototype A UX specification A detailed Functional Prototype V1 developer specification The developer’s job is to turn these into a functional web application. Core requirements include: Mobile-first responsive web app Translate the existing Excel financial model into application code Month-by-month Buy vs. Rent calculations and break-even analysis Duty-station autocomplete accepting military base, city, or ZIP API/data integrations for location-based estimates “Not sure?” options that automatically populate reasonable estimates where supported Current mortgage-rate estimate VA loan and VA funding-fee logic BUY / RENT / ROUGHLY EQUIVALENT result Plain-English explanation of why the result occurred Sensitivity / “what would change the answer?” calculations Editable advanced assumptions Clean mobile UX based on the supplied prototype Accuracy is extremely important. The developer must not replace the Excel model with a simplified calculator. The web implementation must be tested against the supplied Excel model using multiple scenarios, including matching the monthly break-even calculation. I am looking for someone comfortable with full-stack web development, financial/calculator logic, API integrations, and translating Excel formulas/models into code. Please review all attached files before submitting your final quote. In your proposal, please include: Your fixed-price quote Estimated turnaround time Proposed tech stack APIs/data sources you recommend for location autocomplete, local rent estimates, mortgage rates, and eventually BAH Any expected recurring API/hosting costs How you would validate your calculations against the Excel model A link or description of a similar calculator, financial tool, or API-driven web application you personally built The current brand/name in the prototype is a placeholder and may change. Please structure branding so it can be changed easily later. This is Functional Prototype V1. If the developer does excellent work, there is significant opportunity for additional military financial decision tools afterward.

Skills

API Integration Web Application React JavaScript Node.js

Notification History

Channel	Type	Status	Sent	Error
telegram	ai_job_alert	sent	Mon, Aug 17, 2026 5:18 PM	-
telegram	pre_ai_job_alert	sent	Mon, Aug 17, 2026 5:18 PM	-

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