Abdurrahman Yeşilyurt.
tren

Open to new opportunities

AbdurrahmanYeşilyurt

Role
Backend & Full-Stack Software Developer
Focus
.NET · PostgreSQL · Next.js · React Native
Location
Kocaeli, Türkiye
Languages
Turkish · English (C2)
Military service
Completed

Computer engineer building backend systems on ASP.NET Core and PostgreSQL, and equally comfortable on the web and mobile client side with Next.js and React Native. Delivered end-to-end solutions for companies in a range of industries, both in full-time roles and as a freelancer — covering API development, database design, frontend integration, cloud deployment, and CI/CD automation.

Get in touchGitHub LinkedIn

01

Experience

  1. Present

    Backend & Full-Stack Software Developer

    FreelanceKocaeli / RemoteVarious clients
    • Designed and delivered end-to-end backend solutions for multiple companies pursuing digital transformation; owned the process from requirements analysis through production rollout.
    • Built enterprise Web APIs with ASP.NET Core 8, applying layered architecture, dependency injection, DTO patterns, and clean code principles consistently.
    • Designed PostgreSQL schemas and managed migrations with EF Core Code-First; profiled and optimized query performance on live databases.
    • Implemented JWT and HTTP-only cookie authentication, refresh token rotation with token binding (IP, UserAgent), and a role- and permission-based multi-tenant authorization model.
    • Built real-time notification infrastructure with SignalR and integrated transactional email flows through SMTP providers with templated content.
    • Operated Ubuntu servers with Docker container-based deployment, Nginx reverse proxy, SSL certificate setup, and ongoing system maintenance.
    • Designed a CI/CD pipeline with GitHub Actions; published container images and automated SSH deploy so every push triggers a safe release.
    • Developed and maintained multiple web clients (Next.js 15, React, TypeScript, TanStack Query, Tailwind CSS) and a React Native (Expo) mobile app consuming the same backend — taking full-stack ownership end to end.
    • Coordinated with frontend teams on joint projects by preparing DTO contracts, API documentation, and migration guides to streamline integration.
    • Diagnosed production issues through server logs and iterated on improvements based on user feedback.

  2. Backend Developer

    TOS AnalyticsIstanbulIntern → Part-Time (Remote) → Full-Time (Hybrid)
    • Contributed actively to enterprise-grade Web API development with ASP.NET Core; debugged and refactored code together with team members.
    • Worked on PostgreSQL database design, query optimization, and file management integrations with AWS S3.
    • Participated in version control, pull request reviews, and team-wide code quality efforts on Git; took part in testing Web API endpoints and preparing their documentation.
    • Wrote Python scripts for data processing and analysis tasks; integrated AI tools into workflows to automate processes and improve team productivity.

  3. Engineering Intern

    Kocaeli Metropolitan MunicipalityKocaeli
    • Developed internal-use applications on .NET Framework.
    • Worked on server-side configuration tasks under mentor supervision.
    • Gained hands-on experience in Ubuntu server administration and general system management.

  4. Mobile App Developer

    MERLAB Innovation, Science and TechnologyKonya
    • Built a Flutter mobile application for an industrial weighing system.
    • Integrated sensor data from Bluetooth Low Energy devices into the mobile app.
    • Collaborated with the team on the hardware/software interface.

02

Projects

  • EcoYazılım

    Business managementWeb + iOS + Android

    Management platform for environmental and occupational-safety consultancies and their client companies: quote and contract approvals, periodic inspection reports, OHS and environmental consulting, an academy, document tracking and carbon report management — plus a mobile app for field teams.

    My roleThe shared ASP.NET Core 8 API behind the Ekonaz products (SignalR notifications, QR-verified PDF reports with QuestPDF, per-company data isolation and permissions) and the Next.js web app; team development on the Expo mobile app; releases with Docker and GitHub Actions.

    • ASP.NET Core 8
    • PostgreSQL
    • SignalR
    • QuestPDF
    • Next.js 15
    • React Native (Expo)
    • Docker
    • GitHub Actions
    Website App Store Google Play

  • Ekonaz Karbon

    SustainabilityWeb + iOS + Android

    Corporate carbon footprint calculation and reporting portal: activity data per facility and period, Scope 1–3 emission calculations, approved PDF reports and a dashboard with charts, based on ISO 14064 and the GHG Protocol.

    My roleThe backend for formula-based emission calculations and the report approval flow (ASP.NET Core 8), the Next.js customer portal and the iOS/Android app built with Expo.

    • ASP.NET Core 8
    • PostgreSQL
    • NCalc
    • QuestPDF
    • Next.js 15
    • React Native (Expo)
    • TanStack Query
    • Recharts
    Website App Store Google Play

  • Sayvera Global

    E-commerce · Direct sellingWeb

    Direct-selling e-commerce platform for natural health and care products: membership and referrals, a team tree with monthly earnings, a seller marketplace and an extensive admin panel.

    My roleMost of the ASP.NET Core 8 backend: layered architecture, the commission engine (binary tree, career ranks), PayTR payments, e-invoice and shipping integrations, scheduled jobs and GitHub Actions deployment.

    • ASP.NET Core 8
    • EF Core
    • PostgreSQL
    • Identity + JWT
    • AWS S3
    • PayTR
    • GitHub Actions
    Website

  • NakliyeKoop

    LogisticsWeb + Android

    Queue and dispatch system for freight cooperatives: vehicle and driver queues, trip tracking and a freight board. Admins run the queue and trips; drivers follow their place in line live from the mobile app.

    My roleThe Flutter mobile app; most of the NestJS backend (JWT, role-based access, real-time updates over Socket.IO, FCM push) and CI/CD deployment on AWS.

    • Flutter
    • NestJS
    • PostgreSQL
    • Socket.IO
    • Firebase (FCM)
    • Docker
    • AWS Lightsail
    • GitHub Actions
    Website Google Play

03

Skills

Core focus

  • 01Backend

    • ASP.NET Core 8
    • .NET 8
    • Entity Framework Core
    • SignalR
    • Node.js
    • Web API
    • REST
    • LINQ

  • 02Languages

    • C#
    • TypeScript
    • JavaScript
    • Python
    • Dart
    • SQL

  • 03Databases

    • PostgreSQL
    • Relational data modeling
    • Query optimization
    • Migration management

  • 04Frontend

    • Next.js 15
    • React
    • TypeScript
    • TanStack Query
    • Tailwind CSS
    • HTML
    • CSS

  • 05Mobile

    • React Native
    • Expo
    • Flutter

  • 06Identity & Security

    • JWT
    • ASP.NET Core Identity
    • Cookie Authentication
    • Refresh token rotation
    • Role- and permission-based authorization
    • Multi-tenant architecture

  • 07Cloud & DevOps

    • Docker
    • Nginx
    • Ubuntu Server
    • GitHub Actions (CI/CD)
    • AWS EC2
    • AWS S3
    • SSL and domain management

  • 08Tools

    • Git
    • GitHub
    • Swagger/OpenAPI
    • Postman
    • Rider
    • Visual Studio
    • VS Code

  • 09Other

    • QuestPDF (PDF generation)
    • SMTP integrations
    • Python for data processing
    • Bluetooth Low Energy integration

05

Writing

All posts

06

Contact

Have a project or an open role? Let’s talk.