Ivijan-Stefan S.Private profile: Upwork shows its earnings only to signed-in members, so we check it every few weeks, not daily. MRR here is a rough estimate (Upwork's six-month earnings ÷ months active). Last read Nov 5, 2026.

I’m a senior full-stack developer with 20+ years of experience building, maintaining and extending production web systems. PHP has been a constant part of my work throughout my career, together with MySQL, JavaScript, HTML5, CSS3, REST APIs, OAuth, SDK integrations and Linux server environments. A large part of my work involves existing systems rather than greenfield projects. I regularly step into complex codebases, trace problems across the full stack, fix production issues, improve performance, extend existing functionality and integrate external services without disrupting established workflows. My work includes custom backend systems, APIs, payment integrations, authentication and permissions, SaaS workflows, automation, database-heavy applications and long-term platform maintenance. I also have extensive WordPress experience, including custom plugins, themes, WooCommerce development, payment gateways, API integrations and complex application logic. I use WordPress where it makes sense, but I do not depend on off-the-shelf solutions when the business logic requires custom development. In recent years, I have also been working with AI integrations, connecting existing applications with modern AI models, APIs and automation workflows. My focus is on practical implementation: reliable data flow, structured outputs, safeguards, backend integration and maintainable production architecture. Clients typically hire me for: - Taking over and stabilizing existing systems - Complex PHP and backend development - Custom APIs and third-party integrations - Performance and database optimization - SaaS and workflow architecture - AI integrations and automation - WordPress and WooCommerce custom development - Long-term technical ownership and maintenance I’ve worked with startups, agencies and established companies across different markets, both independently and as a lead developer. If you need a senior developer who can understand an existing system quickly, identify the real technical problem and implement a practical solution without unnecessary complexity, I’d be happy to discuss the project.