Full-Stack Web + Mobile • 3-Application Healthcare MVP (38+ Screens)

MedConnect Egypt — Healthcare Platform with AES-256 Blind Indexing & Geofenced Check-Ins

A multi-role healthcare platform balancing private patient records with verifiable clinic workflows.

NestJSPostgreSQLReact NativeAES-256Geofencing

Role: Solo full-stack and mobile systems architect
Production status: Delivered three-application healthcare MVP · 38+ screens
Core stack: NestJS · PostgreSQL · TypeORM · Redis · React · React Native Expo · AES-256-CBC · SHA-256 blind index
Business outcome: Delivered a multi-role healthcare referral workflow that protects patient identifiers and ties clinic attendance to a location check.

The real-world problem

What the system had to solve

Healthcare platforms handle confidential patient records that require encryption, yet clinic staff still need fast database querying across National IDs. Furthermore, physical medical centers suffer revenue leakage from fraudulent referral commission claims when attendants submit unverified manual attendance logs.

What I built

Architecture shaped by the constraints

I architected a unified 3-tier healthcare ecosystem with a NestJS and PostgreSQL backend, React Web administrative portal, and React Native mobile clients for doctors and patients. Patient National IDs use AES-256 encryption with deterministic SHA-256 blind indexing for fast querying, while clinic consultations require GPS geofenced check-ins before referral commissions unlock.

Production proof

Delivered system

Delivered complete multi-role MVP spanning 38+ production UI screens, complete Prisma schemas, and geofence verification tests across mobile and administrative interfaces.

System flow

Architecture at a glance

Doctor and patient apps

React Native clients handle clinical and patient workflows.

NestJS API

Authorization, encrypted records, and geofence checks.

PostgreSQL

Prisma-backed healthcare records with blind-index lookup.

Engineering decisions

Why the system works this way

Encrypted identifiers with blind indexing

Constraint: Encrypting National IDs protects them at rest but removes normal equality lookup, forcing a choice between plaintext storage and expensive full-table decryption.
What I engineered: Stored an AES-256-CBC ciphertext beside a deterministic salted SHA-256 hash with a unique database index.
Production outcome: Kept the identifier encrypted while supporting indexed lookup without decrypting every patient record.

Geofenced clinic check-in

Constraint: Referral commissions depend on attendance, but manual check-ins can be claimed without a verified visit.
What I engineered: Validated secretary GPS coordinates against the registered clinic radius with a Haversine distance check before referral eligibility is credited.
Production outcome: Made the referral handoff auditable against an on-site clinic location.

One API across three client surfaces

Constraint: Doctors, patients, and clinic administrators need distinct workflows without splitting authorization and record rules across disconnected systems.
What I engineered: Built a NestJS API with PostgreSQL and shared domain rules for the React administration portal and React Native doctor and patient apps.
Production outcome: Delivered a coordinated three-application MVP with one consistent healthcare data boundary.

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