Onur Civanoğlu
Senior .NET Backend Engineer | .NET · Distributed Systems · AI/LLM Integration
İzmir, Türkiyeonur.civanoglu@outlook.comlinkedin.com/in/onur-civanoglugithub.com/onurcvnogluonurcivanoglu.com.tr
Professional Summary
Backend engineer with 7+ years of experience designing, building and operating production systems on .NET (C#, ASP.NET Core 8/10). I own services end to end, from domain modelling and API design to Docker-based deployments on Linux, across multi-tenant SaaS, e-learning, e-commerce and e-invoicing domains. Built idempotent, rate-limit-aware integrations with ERP, e-invoicing and payment providers (Paraşüt, Mikro, Uyumsoft, Stripe, PayPal, Paddle, iyzico). Currently focused on LLM-powered product features: provider-agnostic AI gateways (OpenAI, Gemini, OpenRouter), structured JSON outputs, chat assistants, OCR and speech-to-text pipelines, plus AI-assisted engineering workflows with Claude Code, Codex and MCP tooling.
Technical Skills
Languages: C#, TypeScript, JavaScript, SQL (T-SQL), Python
Backend: .NET 8/10, ASP.NET Core Web API, Entity Framework Core, LINQ, Node.js, REST, SOAP/WCF, JWT/OAuth 2.0, FluentValidation, Swagger/OpenAPI, Hosted/Background Services, Quartz.NET, SignalR
AI & LLM: OpenAI API, Google Gemini (Google.GenAI), OpenRouter, Hugging Face Inference, Prompt Engineering, Structured Outputs (JSON Schema), LLM Provider Abstraction / AI Gateway, Conversation Memory, AI Invocation Logging, OCR (Tesseract) + LLM, Speech-to-Text (Amazon Transcribe), Model Context Protocol (MCP), AI-Assisted Development (Claude Code, Codex)
Architecture: Clean/Onion Architecture, Domain-Driven Design, Microservices, Multi-Tenant SaaS, Repository & Unit of Work, SOLID, Idempotency & Distributed Locking, Caching Strategies
Data: MongoDB, MS SQL Server, MySQL, PostgreSQL, Redis, Prisma
Cloud & DevOps: Docker, Docker Compose, Linux Server Administration, Nginx, Apache, IIS, AWS (S3, CloudFront, MediaConvert, Transcribe), GitHub Actions, PM2, DNS/Domain Management
Integrations: Paraşüt, Mikro ERP, Uyumsoft e-Fatura/e-Arşiv, Xentral ERP, Stripe, PayPal, Paddle, iyzico, Firebase Cloud Messaging, SMS/SMTP
Testing & Quality: xUnit, MSTest, Moq, Code Review, Git
Frontend (working knowledge): React, Next.js, React Native/Expo, Tailwind CSS
Work Experience
Backend Developer — Eralp Yazılım A.Ş.
Jul 2023 – Presentİzmir, Türkiye
- Primary backend engineer of a multi-tenant field-sales and CRM SaaS platform (.NET 8, MongoDB, Docker); 1,000+ commits across sales, invoicing, CRM dashboards, lead-ad reporting and push notifications.
- Built resilient ERP and e-invoicing integrations: Paraşüt (token caching, exponential backoff on HTTP 429), Mikro ERP (idempotent order export with distributed locking) and hosted services for e-invoice status synchronization.
- Designed a multi-tenant e-Invoice/e-Archive service on .NET 10 integrated with Uyumsoft, with encrypted credentials, FluentValidation, xUnit/Moq tests and a React admin panel using OpenAPI-generated clients.
- Developed reusable subscription, payment (Paddle, Stripe, PayPal), file management and authentication microservices shared by multiple products.
- Developed and maintained an e-learning platform backend (.NET 8, EF Core/MySQL, Redis) with an AWS S3/MediaConvert/CloudFront video pipeline, iyzico/PayPal/Stripe payments and Quartz scheduled jobs.
- Delivered LLM features: an embeddable Gemini chatbot with prompt management and conversation memory; an AI pre-assessment app that scores leads with OpenAI structured JSON (Next.js, Prisma, PostgreSQL); Tesseract + Gemini OCR and Amazon Transcribe speech-to-text services.
- Improved performance and reliability through statistics read caching, query and index optimizations, cancellation-aware background services and health checks.
- Own Linux server provisioning, Docker deployments, Nginx, DNS/control panel, backups and security hardening; automated production artifact deployments with scripts.
- Introduced AI-assisted engineering practices to the team: repository agent rules (AGENTS.md/CLAUDE.md), reusable skills and documented Claude Code/Codex workflows.
Software Engineer — Arute Solutions A.Ş.
Dec 2022 – May 2023İstanbul, Türkiye
- Built .NET Core REST APIs that serve data produced by background services to UI clients, with Swagger documentation, JWT authentication and role-based authorization.
- Designed database schemas and backend business logic based on requirements and handled server deployments.
Software Developer — Face Yazılım ve Danışmanlık A.Ş.
Jul 2021 – Jun 2022İzmir, Türkiye
- Shipped new database, backend and frontend modules and releases for a commercial CRM product.
- Built REST and WCF web services connecting satellite applications to the core CRM and managed third-party integrations.
- Built a Flutter self-service mobile app for a telecom operator offering bill payment and usage tracking.
Software Developer — Netspeed İnternet A.Ş.
Jul 2019 – Jul 2021Denizli, Türkiye
- Developed the database, backend and frontend layers of the in-house CRM with ASP.NET MVC and MS SQL Server.
- Built dealer management, installation tracking and a configurable call-center bot system.
- Integrated Türk Telekom SOAP services to build an address-based broadband infrastructure and speed lookup system.
Earlier Experience: Tasarım Rehberi (HMS Hotel), Denizli — Software Intern (Jul–Aug 2018): built a MikroTik hotspot network and integrated it with the hotel management software via API.
Selected Projects
Field Sales & CRM SaaS Platform
2023 – 2026Multi-tenant SaaS platform giving field sales teams order, invoicing, customer and CRM management. I am the primary backend engineer and built most of the product across 1,000+ commits.
Tech: .NET 8, C#, MongoDB, Docker, Paraşüt, Mikro ERP, e-Fatura, FCM, Google APIs
Online Academy / E-Learning Platform
2023 – 2026Backend of an e-learning platform with courses, videos, books, events, assignments, quizzes, promotions and subscriptions.
Tech: .NET 8, EF Core, MySQL, Redis, AWS S3, MediaConvert, CloudFront, Quartz.NET, iyzico, Stripe, PayPal
Multi-Tenant e-Invoice / e-Archive Service
2026Multi-tenant e-Invoice/e-Archive service integrated with Uyumsoft, with separate admin and tenant workspaces and a management panel.
Tech: .NET 10, MongoDB, Uyumsoft, FluentValidation, xUnit, Moq, React, Orval, Docker
Subscription, Payment & Shared Microservices
2023 – 2026Subscription management, payment, file management, authentication and e-mail services that different products can integrate with easily.
Tech: .NET 8, MongoDB, EF Core, Paddle, Stripe, PayPal, Serilog, xUnit, Docker
SyncFlowAI — WhatsApp Business AI Flow Platform
2026Backend for a platform that lets businesses build AI-driven conversation flows and lead capture scenarios on WhatsApp Business.
Tech: .NET 10, Clean Architecture, MongoDB, OpenAI, OpenRouter, JSON Schema, JWT, xUnit
Education
B.Sc. in Computer Engineering — Pamukkale University
Sep 2014 – Jun 2019Denizli, Türkiye