Maksim Š.
Senior Full Stack Developer
Experience
Aug 2024 - Aug 2025
1 year 1 monthSenior Full Stack Developer
Kiggla
- Architected and deployed microservices using FastAPI, Django, and Ruby on Rails, supporting AI-based booking and analytics systems across U.S. and European markets. Leveraged containerized environments with Docker to reduce build and deployment time by 60%, ensuring reliability in high-traffic workloads.
- Integrated LLMs and AI APIs (OpenAI, custom embeddings) for automated content generation, recommendations, and anomaly detection. Implemented benchmarking pipelines to evaluate LLM performance in production-like conditions using synthetic data.
- Led code review sessions focused on Ruby and Python services, detecting anti-patterns, improving test coverage with RSpec and Pytest, and enforcing maintainable architecture through metaprogramming and idiomatic coding standards.
- Enhanced CI/CD workflows (GitHub Actions, Jenkins) with automated testing and staging deployments, incorporating static analysis, code quality gates, and container scanning.
- Collaborated with data scientists and solution engineers to fine-tune model behavior through curated annotations, improving output consistency and domain accuracy by 25%.
Jan 2023 - Jul 2024
1 year 7 monthsZagreb, Croatia
Full Stack Developer
Kodelab
- Designed backend services in Python (Django, FastAPI) and Ruby, enabling scalable data workflows and cross-language API integration for real-time analytics and automation products.
- Introduced AI-assisted code generation and linting pipelines using GPT-based systems, enabling semi-automated code review and documentation drafting within the CI process, increasing code quality and reviewer efficiency.
- Optimized PostgreSQL queries and Redis caching, improving throughput by 45% and reducing API response times below 150ms under concurrent load.
- Applied Dockerized test environments and integrated RSpec/Pytest suites within GitHub Actions to achieve faster regression testing and reproducible results.
- Authored detailed technical documentation, including UML diagrams and developer playbooks, standardizing onboarding and cross-project knowledge transfer.
Dec 2021 - Dec 2022
1 year 1 monthZagreb, Croatia
HybridSoftware Developer
Felloz
- Co-engineered a hybrid donation platform with a Python/Django backend and Ruby modules for secure financial transactions, integrating with Stripe and SendGrid APIs to handle real-time events and notifications.
- Developed automated evaluation scripts and Ruby-based CLI tools to monitor code quality and API performance, enabling early bug detection and reducing runtime issues by 30%.
- Implemented Docker-based CI/CD pipelines (GitLab CI) for continuous integration, deployment, and testing, ensuring stable releases and reproducibility across development stages.
- Contributed to prompt design and annotation workflows for internal AI models used to automate donor communications and sentiment analysis, improving classification accuracy and reducing manual QA efforts.
- Collaborated closely with stakeholders and QA to translate business logic into robust service endpoints, validating data integrity and ensuring compliance with security and privacy standards.
Dec 2018 - Nov 2021
3 yearsZagreb, Croatia
Software Developer
Caelor
- Built scalable enterprise web applications and SDKs using Django REST Framework, Node.js, and Ruby components, serving thousands of enterprise users within Atlassian-integrated ecosystems.
- Developed AI-powered assistants and internal automation scripts leveraging GPT-based models and Ruby pipelines to analyze Jira issues and generate knowledge-base content automatically.
- Implemented unit and integration tests (RSpec, Pytest, Jest) integrated into CI/CD pipelines to enforce code reliability and maintain high code health across distributed teams.
- Optimized API performance through profiling and debugging, reducing latency in data-heavy requests and improving system responsiveness by 35%.
- Collaborated cross-functionally with designers, architects, and QA to ensure that architecture and user experience aligned with enterprise security and compliance standards.
Apr 2018 - Dec 2018
9 monthsZagreb, Croatia
Software Developer Intern
Caelor
- Supported senior engineers in building prototype APIs and proof-of-concept services in Python, Ruby, and Express.js, contributing to early-stage product validation and user testing.
- Gained practical experience with Linux-based environments, Dockerization, and Git branching workflows, contributing to smoother deployment processes.
- Participated in debugging sessions and refactoring tasks, learning best practices in object-oriented Ruby programming and code maintainability.
Summary
Versatile Full Stack Developer with 7+ years of experience designing, developing, and optimizing large-scale applications across diverse domains, including SaaS, analytics, and AI-driven systems. Skilled in Python (Django, FastAPI), JavaScript, TypeScript, and Ruby, with a strong focus on clean architecture, data pipelines, and AI integration. Experienced in LLM-based development, prompt evaluation, and automated testing frameworks within CI/CD environments. Adept at collaborating in cross-functional teams, conducting code reviews, and improving model accuracy and reliability through data-driven experimentation. Passionate about building maintainable, well-tested systems that bridge human expertise and intelligent automation.
Languages
Croatian
NativeEnglish
AdvancedEducation
Oct 2014 - Jun 2018
Algebra Bernays University
Bachelor of Science · Computer Science · Zagreb, Croatia
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