Christos S.

Senior Oracle APEX Developer | 10+ Years Experience | PL/SQL | ORDS I am a Senior Oracle APEX Developer with 10+ years of professional experience, specializing in the design, development, modernization, troubleshooting, and support of complex Oracle APEX applications. My primary expertise is Oracle APEX. I build complete business applications from the database layer through to the APEX user interface, including complex workflows, dashboards, approval processes, integrations, security models, document management, notifications, and enterprise administration functionality. I have worked extensively with both new APEX applications and large existing systems where understanding the current architecture, solving complex issues, improving performance, and safely implementing new functionality are critical. Oracle APEX Expertise • Oracle APEX application development and architecture • Complex enterprise and business applications • Interactive Grids and Interactive Reports • Forms, Dashboards, Charts and Data Visualization • Master-Detail and multi-step wizard interfaces • Dynamic Actions and complex client-side behavior • APEX Collections • Shared Components and reusable application components • Authentication and Authorization Schemes • Role-Based Access Control (RBAC) • Application Access Control and security • APEX Workflows, Tasks and approval processes • APEX Automations • APEX_MAIL and HTML email notifications • Application Processes and AJAX callbacks • JavaScript integration and custom APEX functionality • Custom CSS and Universal Theme customization • REST API integrations • REST Data Sources • ORDS RESTful Services • File upload and document-management functionality • OCI Object Storage integration • Application migrations and upgrades • APEX application debugging and troubleshooting • Session-state and page-processing troubleshooting • Performance optimization • Production support and maintenance PL/SQL & Oracle Database A strong APEX application requires a strong Oracle database foundation. I have extensive experience developing the database logic behind enterprise APEX applications. My database expertise includes: • Advanced SQL and PL/SQL • Packages, Procedures and Functions • Triggers and database business rules • Complex SQL queries • Views and Materialized Views • Database constraints and relationships • Data modelling • Data migration and transformation • Performance tuning • Query optimization • Dynamic SQL • JSON processing • Error handling and logging • Scheduled database processes I am comfortable implementing complex business logic in PL/SQL while keeping the APEX application maintainable, secure, and performant. APEX Integrations & Cloud I also have hands-on experience integrating Oracle APEX with external systems and cloud services, including: • Oracle REST Data Services (ORDS) • REST APIs • JSON-based integrations • Oracle Cloud Infrastructure (OCI) • Oracle Autonomous Database • OCI Object Storage • SMTP and APEX email configuration • External authentication and SSO scenarios • Secure API-based integrations Enterprise APEX Applications I have developed and supported Oracle APEX solutions for complex business processes including: • Contract Management Systems • Financial Applications • Workflow & Approval Systems • Construction & Project Management • HR & Performance Management • Regulatory & Registry Platforms • Document Management Systems • Administration Portals • Reporting & Management Dashboards • Role-Based Enterprise Applications What I Can Help You With If you already have an Oracle APEX application, I can help with: • New features and enhancements • Complex APEX bugs and troubleshooting • PL/SQL development • Performance problems • Interactive Grid customization • Dynamic Actions and JavaScript • REST API integrations • Authentication and authorization • Application security • Database design and optimization • APEX upgrades and migrations • UI/UX improvements • Production issues • Ongoing APEX development and maintenance If you are starting a new project, I can design and develop the complete solution — Oracle database, PL/SQL business logic, APEX application, security, integrations, and deployment. Core Technology Stack Oracle APEX | Oracle Database | SQL | PL/SQL | ORDS | OCI | REST APIs | JavaScript | HTML | CSS | JSON I focus primarily on Oracle APEX development and can work independently on complex projects or collaborate with existing development teams. Whether you need a complete APEX application, an experienced developer to extend an existing system, or someone to solve a difficult Oracle APEX/PL/SQL problem, I can help.