11/02/2026 updated
100 % available
Senior C# .NET Developer – ERP & E-commerce Integrations, n8n & AI Automation, Mobile Apps
Tielt-Winge, Belgium
Only remote
Bachelor's: Industrial Engineering (National Defence Univ.); Computer Software Eng. (Marmara Univ.)About me
I'm Selman Altinay, founder of Rui Codex in Tielt-Winge, Belgium. I build business software end to end: C#/ASP.NET Core web apps and APIs, ERP and e-commerce integrations, AI automation and mobile apps. I work remotely and async-first in writing, in short milestones.
OpenAIAzure OpenAIFlutterASP.NETJavaScriptApplication Programming Interfaces (APIs)Android (Software)Microsoft AzureBusiness Process AutomationC Sharp (Programming Language)Mobile Application DevelopmentE-CommerceEnterprise Resource PlanningSupervisory Control and Data Acquisition (SCADA)Python (Programming Language)
Core stack: C#, .NET, ASP.NET Core (MVC, Web API), SQL Server / T-SQL, PostgreSQL, REST API design, Hangfire background jobs, Docker and Azure. JavaScript, HTML and CSS for front ends; Python for scripting and automation.
ERP and integrations: modular web ERP development (purchasing, sales, export, finance, warehouse); real-time marketplace integrations (Trendyol, Hepsiburada, N11) with Netsis accounting, including automated e-invoices and e-waybills; PrestaShop integrations with accounting and four carriers. Also delivered: a B2B dealer ordering platform with live pricing and stock from Netsis accounting, and an Etsy API product-customisation and production platform (Nexcustom).
AI and automation: OpenAI, Azure AI and Claude API integration, LLM workflows and n8n automation. Rui Codex also built and runs EveryTranslate, its own AI translation SaaS.
Industrial data: PLC/SCADA data collection over Modbus for a machining facility (production process tracking).
Mobile: Android and Flutter apps with Firebase and AdMob. Rui Codex publishes its own apps and games on Google Play.
Experience: 12+ years in software development, including 9 years of C#/.NET and SQL Server. Working style: remote, async-first written communication, short milestones; work done inside a client's own system (their ERP, webshop or app) stays there as source code they can use and modify, and Rui Codex's own products and reusable components are licensed for use (a source-code buy-out can be quoted on request). Languages: English (fluent, C1), Turkish (native), Dutch (basic, A2).
Experience
Professional experience10+ years
Freelancer since2026
Languages
EnglishFluentDutchBasic knowledgeTurkishNative speaker
Project history
Software business registered in Belgium (trade name Rui Codex). Builds business software end to end for clients: C#/ASP.NET Core web applications and APIs, ERP and e-commerce integrations, and AI workflow automation (LLM APIs, n8n). Rui Codex also develops and runs EveryTranslate, an AI translation SaaS, and publishes its own Android apps and games on Google Play.
Remote technology lead for a blinds manufacturer (United States). Built internal platforms that work as a custom ERP layer for manufacturing workflows: production tracking, inventory synchronisation and order lifecycle management, with APIs connecting production, logistics and sales.
Part-time, remote (United States). Led backend development of payment and transaction-processing systems: RESTful APIs and service layers, query optimisation and caching, and secure handling of financial data.