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محمد الهجين

@0007580

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Backend engineer building Kawn with Java and Spring Boot; shipped 215+ REST endpoints and load-tested at 1,100+ req/s.

Palestine, State of

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What I'm looking for

I’m looking for a fully remote Java backend role with an international team. Full-time is my first choice, and contract work is also welcome. I work mainly with Java 21, Spring Boot, Spring Security, PostgreSQL and Hibernate, and I enjoy building transactional systems using Domain-Driven Design and modular monoliths. I’m based in Palestine and work remotely only.

I’m independently developing Kawn, a multi-vendor e-commerce marketplace live on AWS EC2. Its backend has 15 domain modules and 215+ REST endpoints, with boundaries enforced by automated architecture tests.

For Kawn’s cart, checkout, and inventory workflows, I implemented atomic inventory updates and a Cart Preview/Reconcile pass to address price and stock conflicts before checkout. Integration tests verified zero overselling under concurrent reservations.

I load-tested the API across three runs of about 99K requests each, reaching 1,100+ requests per second with zero errors. I also built bilingual Arabic/English search and location-aware store filtering using PostgreSQL and PostGIS.

My other backend work includes Sooqna, a graduation project where I led backend architecture and schema design, and Bun Identity, an open-source Spring Boot identity starter with JWT and refresh-token security.

Experience

Work history, roles, and key accomplishments

Current

Independent Backend Engineer

Current

Kawn

Mar 2025 - Present (1 year 7 months)

Sole developer of Kawn, a multi-vendor e-commerce marketplace, designing and implementing the backend independently with 15 domain modules and 215+ REST endpoints. Achieved 1,100+ req/s with zero errors across 299K requests in load tests.