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Yasin YenilAI & SaaS Engineer

About

Hi, I'm Yasin.

Product engineer. Problem solver. Builder of things that ship.

I'm a fullstack engineer based in Krefeld, Germany, with nearly 10 years of experience building software for banking, telecom, ERP and SaaS companies.

Today I focus on applied AI: integrating language models into real products, from OpenAI-powered SaaS features to private LLMs running on-premise, and agentic workflows that guide users and call existing APIs.

I've led teams, passed security audits, and I care about clear communication as much as clean code. I work in English, German and Turkish.

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Experience

  1. 2026 – · Krefeld, Germany

    Freelance AI & SaaS Product Engineer · Yasin Yenil

    Independent. AI integrations, private LLMs, SaaS products and enterprise platforms for clients in Germany and worldwide.

  2. 2026 · Stuttgart / Ulm, Germany

    Senior Fullstack Developer, Enterprise Web & AI · Adelcon

    On-premise LLMs on GPU servers and an AI-guided mode for a .NET MAUI / Blazor app with tool calling; enterprise web platform in Next.js.

  3. 2025 – 2026 · Florida, USA (remote)

    Fullstack Developer & Team Lead · Jaxsuite AI

    Led 5 engineers on a multi-tenant SaaS for 10,000+ users; OpenAI features, payments, WAF, Google CASA, 85% test coverage.

  4. 2023 – 2024 · Istanbul, Türkiye

    Fullstack Developer · QKARE IT

    Credit risk assessment on a core banking platform: 40% faster loan processing, 5% lower default rate.

  5. 2022 – 2023 · Istanbul, Türkiye

    Fullstack Developer · Teleperformance

    AI real-time translation for call center agents, monolith → microservices (DDD), job scheduling that cut manual work by 80%.

  6. 2020 – 2022 · Istanbul, Türkiye

    Fullstack Developer · Adesso Turkey

    ERP finance module with microservices and CQRS; E-Invoice, GIB and Logo / SAP integrations; Silverlight / WCF → .NET Core / REST.

  7. 2018 – 2020 · Istanbul, Türkiye

    Fullstack Developer · Digiturk · Biggloyalty

    Media and loyalty platforms: REST / SOAP services, Oracle and MySQL tuning, telecom and Amazon integrations, Web Forms → .NET Core.

Skills & tools

AI & LLM

OpenAI APIOllama / local LLMsAgentic AITool / function callingRAGPrompt engineeringClaude Code / Codex

Backend

C# / .NET.NET MAUIJavaNode.jsGraphQLEntity FrameworkDapperCQRS / MediatRMicroservices / DDD

Frontend

ReactNext.jsTypeScriptAngularVueBlazorTailwind CSSChrome ExtensionsFigma

Databases

PostgreSQLMSSQLOracleMySQLMongoDBRedisSupabaseFirebaseNeo4jDynamoDB

Cloud & DevOps

AWSAzureGCPDockerCI/CDJenkinsRabbitMQKafkaELKIIS / reverse proxy

Security & Quality

Google CASAOAuthWAFRate limitingGDPRJestPlaywright

Have an idea or a process that eats hours every week?

Let's find out in 30 minutes whether AI or a custom product can fix it, and what it would cost.

Book a free call Or write me an email