Built the Stock Control System (SCS) for Unifree's 23 duty-free stores at Istanbul Grand Airport, a serverless system on AWS Lambda managing real-time inventory and post-purchase stock updates. Developed the Limit Control System (LCS) using Node.js, Fastify, MongoDB, Redis, and RabbitMQ, tracking customer purchases against daily duty-free limits via passport/ID verification. Started building CarrefourSA's backend from scratch as one of two dedicated backend engineers; led the authentication system and designed the order management flow. Delivered backend APIs for Wizzo, a TikTok-style social platform for gamers, using AWS Lambda, Amazon Neptune (GraphDB), and Elasticsearch.

Led a real-time stock integration that enabled Istegelsin warehouses to fulfill CepteSok orders as shared inventory. Built checkout and payment services for CepteSok from the ground up using Kotlin, Spring Boot, and PostgreSQL within a dedicated checkout squad. Worked across Node.js and Kotlin microservices, supporting both platforms through Istegelsin's sunset and CepteSok's launch.

Worked on a serverless e-commerce platform on AWS, progressing from Backend Engineer to Senior. Built and extended GraphQL APIs supporting the full order lifecycle — from cart and checkout through to returns — within a 5–10 person engineering team. As Senior, took on technical planning, knowledge sharing, and onboarding new team members. Integrated Edenred meal card payments via Craftgate API, extending checkout payment options for the platform serving ~1-2K daily orders.

Sole backend engineer on an internal operations platform (employee management, accounting). Designed the serverless architecture on AWS Lambda with DynamoDB and MySQL, collaborating directly with the CTO from technical planning through production. Owned the full backend lifecycle, system design, API development, deployment, and ongoing operations.

Developed backend APIs for BiSU (on-demand water delivery) and BiMarket (grocery marketplace, integrated with Istegelsin) using Node.js and Express.js. Improved test coverage through unit testing and organized manual QA processes, applying QA expertise to strengthen reliability in a fast-moving startup.

Performed functional and performance testing on large-scale digital platforms, including backend validation through SQL-based data verification. Collaborated with engineering teams on test automation, quality processes, and system reliability improvements.

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I build backends that scale.

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