Stjepan is available for hire
Hire StjepanStjepan Buljat
Verified Expert in Engineering
Natural Language Processing (NLP) Developer
Zadar, Croatia
Toptal member since April 8, 2015
Bio
Stjepan is a visionary tech entrepreneur who has scaled companies from zero to multimillion-dollar enterprises and built engineering teams exceeding 120 professionals. Combining technical expertise in Java, Scala, Python, Rust, and AI with strategic business acumen, he transforms innovative concepts into market-leading solutions, shaping the future of enterprise architecture across global markets.
Portfolio
Cognism
Innovation, Innovation Labs, Innovative UX, Rust, Large Language Models (LLMs)...
University of Zadar - Study of Information Technology
TypeScript, NestJS, Python, REST, APIs
Cognism
Amazon Web Services (AWS), Python, Java, Scala, SQL, Twilio API, REST, APIs...
Experience
- Java EE - 7 years
- Project Management - 4 years
- Scrum - 4 years
- Scala - 2 years
- Natural Language Processing (NLP) - 2 years
- Play Framework - 2 years
- MongoDB - 2 years
- Akka - 2 years
Availability
Part-time
Preferred Environment
Git, MacOS, Visual Studio Code (VS Code), Postman
The most amazing...
...startup journey I've led from an idea to a $60+ million company with 120+ engineers, revolutionizing B2B sales with cutting-edge prospecting technology.
Work Experience
Chief Innovation Officer
2023 - PRESENT
Cognism
- Architected and launched Project Orion, a cutting-edge GenAI engine for firmographic data enrichment.
- Led strategic transformation of the innovation team, delivering critical projects including Sales Companion, AI Search (250,000+ monthly searches), and AI Coding initiative that increased development efficiency by 18%.
- Spearheaded major technical transitions, including SingleStore migration and infrastructure optimization, while managing expanded responsibilities across Infrastructure and Architecture teams.
- Deployed Jewel SaaS application with multi-language support and voice control, integrating AI-powered search capabilities across the Cognism platform.
Technologies: Innovation, Innovation Labs, Innovative UX, Rust, Large Language Models (LLMs), OpenAI, LangChain, Snowflake, React, Ant Design, Singlestore, AI Agents, Agentic AI, Artificial Intelligence (AI), Artificial Neural Networks (ANN)
Lecturer - Web Application Development
2019 - PRESENT
University of Zadar - Study of Information Technology
- Developed and delivered comprehensive courses in Python (FastAPI) and TypeScript (NestJS), equipping students with practical skills in modern web development frameworks.
- Designed curriculum covering REST principles, web application architecture, and deployment strategies, preparing students for real-world software engineering challenges.
- Mentored students in building and deploying full-stack web applications, fostering hands-on experience and bridging the gap between academic theory and industry practices.
Technologies: TypeScript, NestJS, Python, REST, APIs
CTO
2015 - 2023
Cognism
- Architected and scaled a robust data platform handling 400+ million records, leveraging Amazon DynamoDB, Elasticsearch, and Kafka to integrate 15+ data vendors for comprehensive business intelligence.
- Led the development of an enterprise-grade prospecting platform with an integrated VOIP calling system, automated email campaigns, and sales intelligence tools, serving 4,000+ global customers.
- Engineered an automated CRM enhancement service achieving 95% data accuracy, enabling validation and enrichment of company records while maintaining GDPR compliance.
Technologies: Amazon Web Services (AWS), Python, Java, Scala, SQL, Twilio API, REST, APIs, Product Management, Software Architecture, Agile Software Development, Akka, Angular, Elasticsearch, Amazon DynamoDB, Redis, Apache Kafka, Kafka Streams, TypeScript, Amazon S3 (AWS S3), Project Management, Linux, Amazon Route 53, Generative Pre-trained Transformers (GPT), Natural Language Processing (NLP), Named-entity Recognition (NER), Event Sourcing, CQRS, Open-source LLMs, Functional Programming, Architecture, System Architecture, System Architecture Design
Play Framework Developer
2016 - 2017
Disruptive Multimedia, Inc.
- Architected a new deployment system using Amazon Elastic Container Services (ECS), improving scalability, reliability, and efficiency for the large-scale messaging application.
- Redesigned service orchestration workflows, streamlining resource management and enabling seamless integration with Akka and Play Framework-based services.
- Optimized infrastructure performance by implementing containerized solutions, reducing deployment time, and enhancing system stability under high traffic loads.
Technologies: Java, JavaScript, Scala, Akka 2, Play Framework, AMQP, IntelliJ IDEA, SBT, GitHub, Git, Heroku, Amazon Web Services (AWS), Redis, Elasticsearch, PostgreSQL, Amazon S3 (AWS S3), WebSockets, REST, Apache Kafka, Cassandra
Product Development Manager
2013 - 2016
Etna
- Established product development function in a service-oriented company, implementing Agile methodologies and leading cross-functional teams to deliver innovative banking solutions.
- Architected BALP analytics platform tracking cross-system banking events, enabling real-time performance monitoring and optimization of business processes across enterprise environments.
- Designed emergency medical services platform with mobile field tracking and centralized dispatch, improving response times and team coordination for ambulance fleets.
Technologies: MongoDB, Akka, Play Framework, JavaScript, Scala, Spring, Project Management
Software Architect
2013 - 2015
Think You, Inc.
- Designed and implemented back-end infrastructure for a social network platform, ensuring seamless integration with mobile apps and wearable devices.
- Developed and deployed APIs to facilitate contact card sharing, enhancing user experience across multiple platforms.
- Managed the entire back-end system solo, collaborating with an iOS engineer to deliver a cohesive user interface.
Technologies: MySQL, spray, Scala, PostgreSQL
Back-end Developer
2013 - 2014
Catchapp
- Implemented a cluster system using Akka Cluster, enabling distributed processing and improved scalability for back-end services, ensuring high availability and fault tolerance.
- Implemented an autocomplete service using the Elasticsearch suggestion feature, optimizing search functionality for faster and more accurate results, enhancing the user experience.
- Created a continuous integration system using Jenkins CI, automating testing and deployment workflows to improve code quality, reduce errors, and accelerate development cycles.
- Migrated an existing database solution to MongoDB, improving data scalability, flexibility, and query performance while ensuring minimal downtime during the transition process.
- Integrated the system with Zabbix, enabling real-time monitoring of system performance, resource usage, and alerts to ensure operational reliability and quick issue resolution.
Technologies: Elasticsearch, MongoDB, Akka, Play Framework, Scala, Linux
IT Architect
2005 - 2013
Etna
- Created a module for printing and sending bank statements to bank customers using Smalltalk and Java.
- Developed a framework for a debt enforcement system within a bank information system using Java EE, WebSphere AS, and DB2.
- Built a module for deposits for legal entities within the existing bank system using Java EE, WebSphere AS, and DB2.
- Created a module for integration to the forex trading system using Java EE, WebSphere AS, and DB2.
- Supported a bank payment application using Smalltalk, VAGen, and DB2.
- Designed and implemented a transactional, modular, and service-oriented framework for a banking application using Java EE and WebSphere AS.
Technologies: IBM Db2, WebSphere Application Server, Java EE, Smalltalk, JasperReports, WebSphere MQ, PHP
Parallel Programming Technology Researcher
2005 - 2005
University of Zagreb Computing Centre
- Worked on a research project on parallel programming technologies alternatives.
- Created multiple MPI programs showcases that run on the Isabella cluster.
- Prepared and held a 3-day course on using MPI on the Isabella cluster.
Technologies: C, MPI
Experience
YouPass
This innovative social network platform simplifies contact sharing through a user-friendly mobile app and wearable bracelet, streamlining professional and personal connections by eliminating the need for physical business cards. Users can easily exchange contact information, manage connections, and stay organized, making networking more efficient and convenient.
RapidEMS
https://www.etna.hr/2014/11/predstavljen-rapidems/RapidEMS is an innovative software system designed to revolutionize emergency medical services management. This comprehensive solution integrates a mobile app for field personnel with a web application for dispatchers, streamlining critical processes and enhancing patient care. Key features include:
Mobile app for emergency responders:
• Real-time navigation optimized for emergency vehicles
• Access to patient medical history through health information exchange (HIE)
• Automated data collection and transmission of vital signs
Web application for dispatchers:
• Advanced computer-aided dispatch (CAD) functionality
• Real-time tracking of responding units and resources
• Integration with hospital systems for seamless patient handoff
Integrated financial management:
• Automated tracking of administered medications and associated costs
• Seamless integration with accounting systems for billing and inventory management
RapidEMS significantly improves operational efficiency, reduces response times, and enhances the quality of care provided by emergency medical services.
Mobile app for emergency responders:
• Real-time navigation optimized for emergency vehicles
• Access to patient medical history through health information exchange (HIE)
• Automated data collection and transmission of vital signs
Web application for dispatchers:
• Advanced computer-aided dispatch (CAD) functionality
• Real-time tracking of responding units and resources
• Integration with hospital systems for seamless patient handoff
Integrated financial management:
• Automated tracking of administered medications and associated costs
• Seamless integration with accounting systems for billing and inventory management
RapidEMS significantly improves operational efficiency, reduces response times, and enhances the quality of care provided by emergency medical services.
Business Activity - Log - Processing (BALP)
https://www.etna.hr/portfolio/balp/BALP is a versatile business analytics and process management tool designed to empower executives with comprehensive insights for effective decision-making. Key features include:
Real-time process monitoring
• Provides a complete overview of business processes
• Enables quick responses to events as they unfold
Flexible data integration
• Supports multiple data sources, both existing and custom-created
• Highly adaptable to specific business needs
Cost-effective solution
• Built on open-source technology
• Eliminates expensive licensing fees and infrastructure investments
Efficient resource utilization
• Leverages existing hardware infrastructure
• Offers rapid return on investment
BALP’s adaptability makes it suitable for various business scenarios, providing executives with the precise insights needed to make impactful decisions and improve overall business performance
Real-time process monitoring
• Provides a complete overview of business processes
• Enables quick responses to events as they unfold
Flexible data integration
• Supports multiple data sources, both existing and custom-created
• Highly adaptable to specific business needs
Cost-effective solution
• Built on open-source technology
• Eliminates expensive licensing fees and infrastructure investments
Efficient resource utilization
• Leverages existing hardware infrastructure
• Offers rapid return on investment
BALP’s adaptability makes it suitable for various business scenarios, providing executives with the precise insights needed to make impactful decisions and improve overall business performance
Education
2007 - 2009
Master's of Business Administration Degree in Business Management
University of Zagreb, Faculty of Economics and Business - Zagreb, Croatia
2000 - 2005
Master's Degree in Computer Science
University of Zagreb, Faculty of Electrical Engineering and Computing - Zagreb, Croatia
Certifications
MARCH 2024 - PRESENT
Fundamentals of NestJS
Board Infinity
NOVEMBER 2013 - PRESENT
SpringSource Certified Spring Professional
SpringSource
JULY 2013 - PRESENT
Certified Scrum Master
Scrum Alliance
MARCH 2008 - PRESENT
Sun Certified Programmer for the Java Platform, SE 5.0
Sun Microsystems
Skills
Libraries/APIs
JasperReports, spray, MPI, Twilio API, React, AMQP
Tools
Git, IntelliJ IDEA, SBT, Named-entity Recognition (NER), Kafka Streams, GitHub, Postman
Languages
Java, Scala, SQL, JavaScript, C, Smalltalk, Python, Rust, TypeScript, Snowflake, Java 5, PHP
Frameworks
Akka, Play Framework, AngularJS, Spring, Angular, Ant Design, NestJS, Akka 2, Kendo UI
Paradigms
Scrum, REST, Agile Software Development, Event Sourcing, CQRS, Functional Programming, Management
Storage
MongoDB, PostgreSQL, MySQL, Elasticsearch, IBM Db2, Amazon DynamoDB, Redis, Amazon S3 (AWS S3), Cassandra
Platforms
Amazon Web Services (AWS), Java EE, Linux, MacOS, Visual Studio Code (VS Code), Apache Kafka, Heroku, WebSphere MQ, Mobile
Industry Expertise
Project Management
Other
Product Management, Software Architecture, APIs, Open-source LLMs, WebSphere Application Server, Amazon Route 53, Natural Language Processing (NLP), Generative Pre-trained Transformers (GPT), Business to Business (B2B), Web Marketing, Finance, Programming, Analytics, Neural Networks, Innovation, Innovation Labs, Innovative UX, Large Language Models (LLMs), OpenAI, LangChain, Certified ScrumMaster (CSM), WebSockets, Web App Development, Web Servers, Architecture, System Architecture, System Architecture Design, Singlestore, AI Agents, Agentic AI, Artificial Intelligence (AI), Artificial Neural Networks (ANN)
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