Hossam Elharmeil
Verified Expert in Engineering
Full-stack Developer
6th of October City, Giza Governorate, Egypt
Toptal member since April 8, 2026
Hossam is a senior full-stack developer with over eight years of experience architecting sophisticated SaaS systems for high-stakes industries. He specializes in designing robust system architectures that handle complex workflows with precision and scale. Hossam is committed to delivering reliable, high-performance solutions built for large-scale environments. During his time at McKinsey & Co, he developed a solution to manage stock shortages that reduced back-office workloads by 40%.
Portfolio
Experience
- React - 8 years
- Node.js - 8 years
- PostgreSQL - 7 years
- Google Cloud Platform (GCP) - 7 years
- TypeScript - 6 years
- Expo - 5 years
- React Native - 5 years
- NestJS - 3 years
Preferred Environment
Node.js, TypeScript, React, React Native, Expo, PostgreSQL, NestJS, GitHub Copilot, Docker, Jira
The most amazing...
...system I've built is a veterinary and pet parent ecosystem that enables veterinarians to run their clinics and pet parents to track their pets' health.
Work Experience
Senior Full-stack Developer
McKinsey & Company
- Developed shop owner and delivery driver mobile apps that facilitate ordering and delivering goods for small grocery stores.
- Architected back-office applications for managing invoicing, refunds, and inventory operations.
- Created an automatic out-of-stock calculation algorithm that allows back-office personnel to enter the available amount and automatically modify orders through proportional distribution, which saved eight hours a week of manual modification.
React Native Developer
Watson Creative
- Engineered an app that matches users with life coaches and enables them to create a life plan and work towards achieving their goals.
- Built an interactive UI for users to create life accounts, such as health, money, spirituality, etc. Users can answer questions in a smooth, reflective experience that helps them create their goals.
- Optimized performance by extracting and rewriting a heavy load operation into an autoscaling microservice, reducing latency by 40%.
Full-stack Developer
Atini Studio
- Developed a homeowner association system for managing homeowners' association (HOA) documents, meetings, and events.
- Built a system for matching employers with fit candidates based on skills and common interests.
- Created a web application for golf coaches to list their availabilities and accept bookings and payments.
Mobile App Developer
Cantina Eats
- Developed an application that enables users to order vacuum-sealed meals.
- Created a back-office dashboard for managing and delivering orders.
- Implemented analytics to track and improve user engagement, which resulted in 35% increase in orders.
Experience
Vetrie | Ecosystem for Veterinarians and Pet Parents
https://vetrievms.comAdopting an API-first approach, Hossam built a comprehensive developer portal for managing integrations. The documentation site cut the time it takes to integrate with a 3rd party tool by 50%
ATC+ | A Logistics Suite
https://play.google.com/store/apps/details?id=shop.emaxi.ma&pli=1Key highlights of my work included a gamified flash sale UI, where users see a floating circle that tracks their progress toward discount eligibility. I also developed an out-of-stock batch processing feature that allows back-office personnel to input available product quantities, with the system automatically adjusting orders through proportional distribution.
SetPath | Life Coaching App
https://setpath.orgEducation
Bachelor's Degree in Computer Systems Engineering
Nile University - Sixth of October, Egypt
Certifications
Stripe Professional Payments Developer
Stripe
OpenAPI: Beginner to Guru
Udemy
React (Basic)
Hacker Rank
Developing Applications with Google Cloud
Coursera
Server-side Development with Node.js, Express, and MongoDB
Coursera
Skills
Libraries/APIs
Node.js, React, Vue, Google Maps, Stripe, REST APIs, API Development, Auth, Socket.IO, OpenAPI
Tools
Expo, Git, Jira, GitHub, GitHub Copilot, TanStack Router, Claude Code, Vitest, Shadcn UI, Shadcn, Nx, OneSignal
Languages
TypeScript, JavaScript, CSS, HTML, Python, C++
Frameworks
React Native, NestJS, Express.js, Tailwind CSS, Next.js, Redux, Flutter, Svelte, Angular, Jest, tRPC
Paradigms
Mobile Development, Component-based Development, Test-driven Development (TDD), B2B, Microfrontends, UI Design
Platforms
iOS, Docker, Vercel, Firebase, Amazon Web Services (AWS), Google Cloud Platform (GCP), Cloud Run, Commercetools, AWS Lambda, Azure, Android
Storage
PostgreSQL, MySQL, PostGIS, Database Architecture, Amazon S3 (AWS S3), Data Pipelines, Databases, Google Cloud SQL, MongoDB
Other
Mobile App Development, Software Development, Mobile UI, Software, Front-end, APIs, API Integration, Vibe Coding, Software Architecture, AI Tools, Full-stack, Payments, Figma to React, OAuth, System Architecture, GeoJSON, Geospatial Data, Spatial Data Infrastructure, CI/CD Pipelines, Technical Architecture, Minimum Viable Product (MVP), Web Development, Early-stage Startups, AI-generated Code, React Hooks, Full-stack Development, RESTFul APIs, Architecture, Mobile Apps, Software as a Service (SaaS), Software Design, Zustand, Webhooks, Dashboard Design, Tanstack, ChatGPT API, Large Language Models (LLMs), Vite, Supabase, Artificial Intelligence (AI), Generative Artificial Intelligence (GenAI), Marketplaces, Performance Optimization, SaaS, GitHub Actions, OpenAI, AI Integration, API Gateways, Railway, Legacy Software, Financial Systems, WebSockets, Algorithms, Computer Architecture, HTTP, Amazon Bedrock, Styled-components, Storybook, App Store Connect, Google Play Store, Payment APIs, Card Payments, eCommerce, Stripe Payments, Setup Intents, Payment Intents
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