Hire the Best API Integration Freelancers
in Turkey

I build and integrate backend APIs using C#, ASP.NET Core Web API, SQL, PostgreSQL, and REST-based services. I can help with third-party API integration, REST API development, backend bug fixes, database-connected endpoints, authentication-related tasks, Swagger/OpenAPI documentation, and API testing. My portfolio includes an ASP.NET Core Weather API Wrapper with external API integration, Redis caching, standardized error handling, Swagger documentation, and HTTP resilience policies such as retry, timeout, and circuit breaker. I also have an e-commerce API project using ASP.NET Core, Entity Framework Core, PostgreSQL, JWT authentication, and Docker Compose. Services I can help with: • ASP.NET Core Web API development • Third-party API integration • REST API design and implementation • SQL / PostgreSQL backend work • JWT authentication • Swagger / OpenAPI documentation • API testing and debugging • Backend maintenance and bug fixing I focus on readable code, practical implementation, and clear communication.

Solo founders and small businesses often run payment systems, CRMs, and data workflows that don't talk to each other. I connect these systems and fix them when they break. Typically I work with Stripe, PayPal, Square, WooCommerce Payments, Monday CRM, and custom API integrations. Most of my clients come to me with one of two situations. Either they have a payment, CRM, or data flow that needs to be connected to another system from scratch — or they have an existing integration that suddenly stopped working and they need it fixed fast. I handle both. What I don't do is generic web development or building from zero. My focus is the connection layer: where two or three systems meet and need to exchange data reliably. This is where most projects break, and this is where I spend my time. Typical projects I take on: - Stripe, PayPal, or Square integration on existing websites (including Square Send Link flows for service-based businesses) - WooCommerce subscription and payment fixes when renewals or webhooks fail silently - Connecting Monday CRM with websites, payment systems, or external databases for two-way data sync - Custom automation between tools using n8n, Make, or PHP/Python scripts - Database cleanup and SQL work when the data inside these systems gets messy after migrations or integrations I work fast on small to mid-sized projects (a few days up to two weeks). I communicate clearly, send progress updates without being asked, and test integrations against real edge cases before delivery — not just the happy path. If you have a system that should be talking to another system but isn't — or used to work and now doesn't — send me a message. I'll take a look and tell you honestly whether it's a quick fix or something bigger.