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I am a Senior Software Developer with extensive experience designing, building, and supporting large-scale healthcare integrations. I specialize in Rhapsody Integration Engine v6+, Symphonia Mapping Language (SML), HL7 v2.x messaging, and secure data exchange across public health, laboratory, and disease surveillance systems. I enjoy modernizing legacy processes, driving reliability, and collaborating with teammates and stakeholders to deliver high-impact health IT solutions. In my roles, I lead complex integration initiatives, implement ETL and automation, and apply strong SQL and JavaScript skills to transform and validate data. I’m passionate about quality, compliance (HIPAA, CDC, CJIS), and creating maintainable, scalable systems in DevOps environments while mentoring others and sharing best practices.…I am a Senior Software Developer with extensive experience designing, building, and supporting large-scale healthcare integrations. I specialize in Rhapsody Integration Engine v6+, Symphonia Mapping Language (SML), HL7 v2.x messaging, and secure data exchange across public health, laboratory, and disease surveillance systems. I enjoy modernizing legacy processes, driving reliability, and collaborating with teammates and stakeholders to deliver high-impact health IT solutions. In my roles, I lead complex integration initiatives, implement ETL and automation, and apply strong SQL and JavaScript skills to transform and validate data. I’m passionate about quality, compliance (HIPAA, CDC, CJIS), and creating maintainable, scalable systems in DevOps environments while mentoring others and sharing best practices.

Marko Zeljko

Full Stack Developer, Web Developer, Back-End Developer, +4

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I am a Senior Software Developer with extensive experience designing, building, and supporting large-scale healthcare integrations. I specialize in Rhapsody Integration Engine v6+, Symphonia Mapping Language (SML), HL7 v2.x messaging, and secure data exchange across public health, laboratory, and disease surveillance systems. I enjoy modernizing legacy processes, driving reliability, and collaborating with teammates and stakeholders to deliver high-impact health IT solutions. In my roles, I lead complex integration initiatives, implement ETL and automation, and apply strong SQL and JavaScript skills to transform and validate data. I’m passionate about quality, compliance (HIPAA, CDC, CJIS), and creating maintainable, scalable systems in DevOps environments while mentoring others and sharing best practices.…I am a Senior Software Developer with extensive experience designing, building, and supporting large-scale healthcare integrations. I specialize in Rhapsody Integration Engine v6+, Symphonia Mapping Language (SML), HL7 v2.x messaging, and secure data exchange across public health, laboratory, and disease surveillance systems. I enjoy modernizing legacy processes, driving reliability, and collaborating with teammates and stakeholders to deliver high-impact health IT solutions. In my roles, I lead complex integration initiatives, implement ETL and automation, and apply strong SQL and JavaScript skills to transform and validate data. I’m passionate about quality, compliance (HIPAA, CDC, CJIS), and creating maintainable, scalable systems in DevOps environments while mentoring others and sharing best practices.

Available to hire

I am a Senior Software Developer with extensive experience designing, building, and supporting large-scale healthcare integrations. I specialize in Rhapsody Integration Engine v6+, Symphonia Mapping Language (SML), HL7 v2.x messaging, and secure data exchange across public health, laboratory, and disease surveillance systems. I enjoy modernizing legacy processes, driving reliability, and collaborating with teammates and stakeholders to deliver high-impact health IT solutions.

In my roles, I lead complex integration initiatives, implement ETL and automation, and apply strong SQL and JavaScript skills to transform and validate data. I’m passionate about quality, compliance (HIPAA, CDC, CJIS), and creating maintainable, scalable systems in DevOps environments while mentoring others and sharing best practices.

Skills

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Expert

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Intermediate

Language

English

Fluent

Work Experience

Senior Software Engineer at CoDigit

September 1, 2022 - October 1, 2025

Led development of MVP and early production features using React and TypeScript, collaborating with product owners and designers to refine user flows. Designed and implemented REST and GraphQL APIs in Node.js and Python, supporting consumer features and internal tooling. Built backend services prioritizing clarity and flexibility to accommodate evolving product direction. Integrated AI-powered and LLM-based chatbot features into user workflows, managing prompt logic, latency, and failure scenarios. Collaborated with designers to translate Figma concepts into onboarding-focused UI. Developed API layers for web and iOS clients with consistent authentication and versioning. Designed and optimized PostgreSQL schemas to support personalization, analytics, and reporting. Implemented logging, basic monitoring, and production safeguards early in lifecycle. Took ownership end-to-end from scoping to deployment and post-launch iteration. Balanced delivery speed with maintainable code to keep the

Senior Full Stack Developer at Google

June 1, 2019 - August 1, 2022

Contributed to large-scale internal web applications using React frontends and Python / Node.js backend services. Built and maintained APIs supporting multiple client types, including web dashboards and mobile applications. Worked closely with UX designers and product managers to translate ambiguous ideas into concrete, testable features. Implemented backend logic for data-driven and personalized user experiences. Helped develop experimentation and rollout mechanisms to validate new product ideas safely. Participated in architecture reviews focusing on scalability, reliability, and long-term evolution. Wrote automated tests to protect critical flows during rapid iteration. Improved internal developer tooling and documentation to speed feature delivery. Gained experience operating systems with strict performance and reliability expectations. Shaped incremental value without blocking for perfection.

Software Engineer at Combis

April 1, 2015 - May 1, 2019

Developed and maintained full-stack web applications with JavaScript frontends and backend services in Python and Ruby. Built early-stage product features under fluid requirements with rapid delivery. Designed relational data models supporting operational workflows and reporting. Implemented background job processing for long-running or AI-adjacent tasks. Collaborated with business stakeholders to clarify problems before committing to technical solutions. Diagnosed and resolved production issues by analyzing logs and runtime behavior. Contributed to API designs that supported mobile and third-party integrations. Introduced unit and integration testing practices to reduce regressions during fast development cycles. Helped evolve internal tools into customer-facing products and built a strong pragmatic engineering foundation for growing startups.

Full Stack Developer at Aiticon

June 1, 2022 - October 1, 2025

Senior technical lead for Rhapsody Integration Engine v6+, designing, configuring, and maintaining complex routes supporting public health and laboratory data exchange. Developed and enhanced Symphonia Mapping Language (SML) transformations to process HL7 v2.3.1–2.5.1 messages (ORU and ORM). Built and maintained JavaScript-based transformations to normalize and enrich HL7, XML, CSV, and SOAP payloads. Designed new Rhapsody routes and refactored legacy integrations to meet coding standards, performance benchmarks, and security requirements. Implemented SOAP web service integrations for bidirectional data exchange with external partners and vendors. Created advanced SQL queries to validate data, reconcile records, and support reprocessing workflows. Monitored production routes via the Rhapsody Web Management Console, identified throughput issues, latency bottlenecks, and data anomalies. Led troubleshooting, root-cause analysis, and safe data reprocessing. Advised teams on routing, tran

Full Stack Developer at Creatif Agency

April 1, 2020 - May 1, 2022

Designed and implemented Rhapsody-based ETL solutions for healthcare data ingestion, transformation, and delivery to surveillance and reporting systems. Developed SML and JavaScript transformations to standardize inbound data for agency and CDC requirements. Built SOAP-based integrations with reliable parsing, error handling, and retry logic. Collaborated with public health stakeholders to elicit requirements, perform gap analyses, and translate them into technical specs. Assisted with migrating and rewriting existing integrations into Rhapsody to improve maintainability and long-term support. Created and maintained documentation, architecture diagrams, and data-flow specs. Supported Windows Server environments, assisting with Rhapsody upgrades and environment provisioning. Participated in code reviews, enforcing coding standards and performance guidelines. Implemented SQL-based validation checks to ensure accuracy prior to submission to surveillance systems. Provided mentoring to juni

Web Engineer at InHouse Digital

December 1, 2017 - March 1, 2020

Supported early healthcare integration efforts involving HL7 message processing, XML transformations, and relational database validation. Developed data pipelines for moving laboratory and clinical data between source systems and public health platforms. Wrote SQL queries to analyze inbound datasets, verify transformations, and support reconciliation activities. Built basic JavaScript and XML processing logic for early integration workflows. Participated in testing, validation, and deployment activities to ensure transformed data met agency formatting and content requirements. Assisted with monitoring, error correction, and controlled reprocessing of failed transactions. Gained exposure to public health data systems, compliance requirements, and secure data handling practices.