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Full Stack Developer

Hi, I'm Sefa Yılmaz

Midlaner

Experienced Full Stack Developer with 4 years in software development, from Junior to Midlaner. Skilled in .NET Core, React, Node.js, and modern web technologies. Focused on clean architecture, scalable systems, and developing web and mobile applications from scratch.

Currently Working
📍 Istanbul, Turkey

Professional Experience

My journey in software development

Midlaner

Full Stack Developer

May 2022 - Present
Full-time

Experienced Full Stack Developer with 4 years in software development, from Junior to Midlaner. Skilled in .NET Core, .NET Core MVC, C#, React, React Native, MySQL, MSSQL, NoSQL, MongoDB, PostgreSQL, HTML, CSS, JavaScript, Node.js, PHP (CodeIgniter & Laravel), RESTful API development, Laravel API, Bootstrap, TailwindCSS, Next.js, Nest.js, Hono.js, Python Web API, Electron.js, and Nuxt.js. Focused on clean architecture, scalable systems, and developing web and mobile applications from scratch.

Key Highlights:

  • Developed scalable full-stack applications
  • Architected clean and maintainable codebases
  • Implemented clean architecture principles
  • Developed web and mobile applications from scratch

Software Developer

Freelance / External Professional

January 2015 - May 2022
Freelance

Freelance Full Stack Developer with experience in E-Commerce, Accounting, and B2B applications. Skilled in JavaScript, PHP (CodeIgniter), MySQL, PostgreSQL, and RESTful APIs. I develop clean, maintainable, and scalable web and mobile solutions tailored to client needs.

Key Highlights:

  • Developed E-Commerce platforms
  • Built Accounting systems
  • Created B2B applications
  • Delivered custom web and mobile solutions

Technical Skills

Technologies and tools I work with

Backend Development

.NET Core / .NET Core MVC
Expert

5 years

C#
Expert

5 years

Node.js
Expert

1 year

PHP (CodeIgniter & Laravel)
Expert

10 years

Python Web API
Intermediate

1 year

Nest.js
Intermediate

1 year

Hono.js
Intermediate

1 year

Frontend Development

React
Advanced

2 years

Next.js
Advanced

2 years

JavaScript
Expert

9 years

HTML
Expert

10+ years

CSS
Expert

10+ years

Bootstrap
Expert

10 years

TailwindCSS
Intermediate

1 year

Nuxt.js
Intermediate

<1 year

Mobile Development

React Native
Advanced

2 years

Flutter
Intermediate

1 year

Electron.js
Intermediate

1 year

Databases

MySQL
Expert

10+ years

MSSQL
Expert

5 years

PostgreSQL
Expert

2 years

MongoDB
Expert

1 year

NoSQL
Advanced

2 years

Other Technologies

RESTful API Development
Expert

5 years

JAVA
Advanced

1 year

Git / GitHub
Advanced

5 years

Expertise

Clean Architecture
Expert

3 years

Scalable Systems
Advanced

3 years

E-Commerce Development
Expert

5 years

B2B Applications
Advanced

4 years

Education & Certifications

Academic background and professional development

Education

Web Design and Coding

Istanbul University

September 2024 - Present
In Progress

Bachelor's Degree

Electric

Istanbul Aydin University

September 2021 - September 2023
Completed

Bachelor's Degree

Certifications

C1 Level English

BTK Academy

2025
19 hours

Languages

English

Written:
High
Spoken:
Negotiation Level

Turkish

Written:
Native
Spoken:
Native

Projects

Some of my notable work

Featured

C1 Patron - CRM System

Mobile CRM

A comprehensive CRM (Customer Relationship Management) mobile application built with Flutter. Features include customer management, sales tracking, appointment scheduling, and real-time analytics. Available on iOS App Store.

Flutter
Dart
Firebase
REST API
View Project
Featured

Payment Gateway System

FinTech

Enterprise payment gateway integrating all major virtual POS systems and banks. Built with Clean Architecture principles, providing secure payment processing, transaction management, and real-time monitoring. Supports multiple payment providers and currencies.

.NET Core MVC API
MSSQL
Next.js
Clean Architecture
Featured

SaaS Accounting Software

SaaS / Business

Cloud-based SaaS accounting solution designed with Clean Architecture. Features include invoicing, expense management, financial reporting, multi-company support, and real-time analytics. Scalable and secure for businesses of all sizes.

.NET Core MVC API
MSSQL
React
Clean Architecture
Featured

Affiliate Marketing System

Marketing Platform

Complete affiliate marketing platform built with Clean Architecture principles. Manages affiliate programs, tracks conversions, handles commission calculations, and provides detailed analytics. Features real-time reporting and automated payment processing.

.NET Core MVC
MSSQL
Clean Architecture

B2B Management System

Enterprise Software

Comprehensive B2B application for managing business relationships, orders, and inventory. Built with Clean Architecture, includes real-time updates and reporting features.

.NET Core
C#
MSSQL
React
Clean Architecture

E-Commerce Platform

Web Application

Full-stack e-commerce solution with admin panel, product management, shopping cart, and payment integration. Built with modern technologies for scalability and performance.

React
Node.js
PostgreSQL
TailwindCSS

Get In Touch

Let's work together on your next project

I'm currently available for freelance work and full-time opportunities. If you have a project in mind or would like to discuss potential collaboration, feel free to reach out!

Location

Istanbul, Turkey

Connect with me