Hi, I'm
Amr Mohamed
I studied dentistry for five years, but halfway through I started learning to code as a hobby and couldn't stop. Five years of backend later: ad-tech, fintech, healthcare. The problems I enjoy most are the ones other people avoid.
Here's what that looks like in production:
Senior Backend Engineer
Cairo, Egypt
Recent Work
A few systems I've built and shipped — newest first. Each one links to a short write-up of what the problem was and how I solved it.
01 / Featured Project
Booklnk
Multi-tenant appointment booking backend serving barbershops, gyms, and consultants — built from scratch on NestJS + PostgreSQL. I owned the architecture end-to-end.
02 / Featured Project
Kashier
Payment infrastructure work — WooCommerce plugins used by thousands of merchants, a URL shortener that cut SMS costs by 25%, and the documentation that made the whole thing easier to integrate.
03 / Featured Project
Outlier
Backend performance work on an edtech platform — cut a 3-minute cronjob to 45 seconds, dropped average query time by 40%, and built the student account merge tool nobody wanted to touch.
04 / Featured Project
Umedmi
Built a patient management platform from scratch — schema design, API, AWS infrastructure, ICD-10 medical code engine, real-time chat, and payment integration. Three years of real healthcare system engineering.
My Path Into Backend
Dentistry didn't take. Backend did.
I picked up programming as a hobby in dental school and it quietly took over. Five years later I've shipped backends in ad-tech, fintech, and healthcare — the kind of systems where a bad night means real money or real patients, not a missed sprint.
Most of my work is in Node.js and NestJS. I keep clear boundaries between modules and design the database carefully up front, because the real cost of a system isn't writing it — it's the next engineer trying to change it six months later. Monitoring, CI/CD, and boring, predictable deploys are part of the job, not an afterthought.
I keep one eye on the bill and one on the user. Cutting infra cost, shaving a few hundred milliseconds off a hot path, or deleting a workflow nobody needed — that's the work I actually enjoy.
Work Experience
Timeline
Senior Backend Engineer
·ThunderOct 2025 — Present·Remote
- Migrated the ad-tracking event pipeline from RabbitMQ to GCP Pub/Sub — now processing ~1M events/day. Chose Pub/Sub over Kafka after weighing operational overhead against our team size.
- Designed and hardened core backend services in Express.js and PostgreSQL, focused on API reliability and performance under peak traffic.
- Added retry logic and dead-letter queues to the messaging layer so we don't lose ad events.
Backend Engineer
·BookLnkContractJan 2025 — Sep 2025·Remote
- Architected the backend from scratch for a multi-tenant booking platform (barbershops, gyms, consultants) — owned schema, service layer, and the full API surface on NestJS + PostgreSQL.
- Implemented concurrent-booking protection with optimistic locking — slot conflicts were surprisingly non-trivial across time zones and overlapping service durations.
- Integrated Kashier for payments — webhook handling, transaction validation, and reconciliation, working reliably end to end.
Integration Engineer
·KashierJul 2024 — Jan 2025·Hybrid·Cairo, Egypt
- Maintained WooCommerce payment plugins used by thousands of merchants — bug-fixing and keeping things working with the block editor and HPOS.
- Improved API and plugin documentation to streamline developer onboarding and merchant integration.
- Built a URL shortener service — sounds simple, but it saved about 25% on SMS costs across the platform.
Backend Engineer
·OutlierContractSep 2023 — Jun 2024·Remote
- Optimized a complex cron job, cutting execution time from 3 minutes to 45 seconds.
- Ran advanced database query optimizations — 40% reduction in average query time on high-traffic endpoints.
- Built a tool to merge duplicate student accounts — harder than it sounds: remapping relationships across 12+ tables without losing data.
Backend Engineer
·UmedMiMar 2020 — Aug 2023·Remote
- Built a patient management system from the ground up — data model, API layer, and cloud infrastructure for a healthcare platform handling sensitive medical data.
- Designed an ICD-10 medical code parsing engine that turned complex diagnostic codes into interactive, searchable cards — cutting clinical lookup time for providers.
- Owned AWS production infrastructure (EC2, S3, IAM) with security groups, automated backups, and monitoring for HIPAA-aligned deployments.
Tech Stack
Skills
Certifications & Professional Credentials
AWS Certified Solutions Architect – Associate (SAA-C03)
Validates expertise in designing distributed systems, cost-optimized architectures, and resilient applications on AWS infrastructure.
Verify CredentialWhat I Can Help With
I take on a handful of backend and cloud projects at a time. If any of these sound like your situation, we'll probably work well together.
“My API is slow and I don't know why.”
“I need payments working before launch.”
“My AWS bill makes no sense.”
“We need an API built from scratch.”
“Our deploys are scary and manual.”
“The codebase is a mess to change.”
How I Work
I work best on longer engagements where I can actually learn the domain — not one-off tickets.
Get in TouchFeatured Blogs
Contact Me
Hiring, building something, or just want a second opinion on an architecture decision? Drop me a line — I read every message and reply to the real ones.
Contact Information
Open to new projects and senior backend roles.