Volunteer App Developer — Nonprofit Health Tech - Complete Tech Build Spec

Circle Signal is a free psychosocial communication app for cancer patients in active treatment. A patient writes one update and sends it to tiered circles of support — Inner Circle, Support Circle, and Community. Recipients respond with one emoji only. No text replies. Always free for patients.

A working interactive prototype is live at circlesignalapp.netlify.app

The frontend is done. We need one volunteer backend developer to build the complete data layer.

What needs to be built:

• Phone number authentication with SMS verification
• Database for users, contacts, updates, and reactions
• Three circle tiers per patient with unique private recipient links
• Emoji-only reaction system — no text replies possible
• One-tap "I'm resting" status button
• Gifting feature so supporters can purchase Circle Signal for a patient
• Stripe integration for supporter subscriptions
• Twilio SMS with full 10DLC carrier registration
• HIPAA-adjacent privacy and security design

Tech stack: Node.js or Python, Supabase, Twilio, Stripe, Vercel

Time commitment: 4-6 weeks, fully remote, flexible schedule

Why this matters: The founder is a breast cancer patient building this during active treatment. 1.9 million new cancer diagnoses in the US every year. No existing tool protects the patient's energy the way Circle Signal does. Every week without it is another patient managing 47 text messages from a hospital bed.