Slaven Ostojić.

ZIRA, Tuzla » System architect

May 2023 - Present

• Working on client-facing, microservice, distributed, enterprise solution for the leading provider of telecommunications services in Saudi Arabia
• Working on electronic invoicing product integrated with ZATCA and improving existing system through automation and optimisation (i.e. speed-up validation process up to 100 times)
• Designing and developing marketplace solutions that integrate suppliers, customers, and internal users seamlessly via TMF API
• Leading the development team accountable for software delivery
• Developing internal tools to improve software maintenance process and reporting
• Developing CI/CD pipeline using GitLab CI/CD

Salt Square, Tuzla » Senior software engineer

March 2022 - May 2023

• Designing and developing large-scale projects for different clients, working on front-end, back-end, database and infrastructure layers
• Designing and developing a full-stack solution as a central consumer portal for one of the leading domestic appliances company
• Creating architecture and design, developing and testing feature flag service with custom and non-trivial condition logic used in the health-care industry
• Working on and owning several features and domains in a large-scale, full-stack and HIPAA-compliant solution for COVID testing management in highly regulated US health-care industry
• Designing and developing inventory register with Google SSO
• Creating web scrapers deployed in AWS with Terraform
• Mentoring younger colleagues and teaching them Unit testing and Spring Boot

Infobip, Tuzla » Software engineer

April 2019 - February 2022

• Working on distributed, data intensive enterprise microservice applications with main focus on stability, high availability, geo-redundancy, scalability and security
• Development and maintenance of Mobile number portability system for collecting raw data from FTP, SFTP, HTTP, HTML, email, S3, etc. sources, uniforming and storing processed data in database for fast and intensive read operations
• Maintaining and improving the USSD platform with over 3 million concurrent sessions in Africa
• Development of Voice bot solution with DTMF functionality, with focus on end-to-end testing
• Analyzing Email platform in order to redesign it to scale up and support 10x more traffic
• Organising and leading internship in the company
• Mentoring younger colleagues

Marvelsoft, Tuzla » Senior software developer

September 2014 - March 2019

• Developing real-time, event-based, multithreaded, computation and data intensive systems for algo trading solution, used mainly in Europe and Asia.
• Designing and developing order management system with main focus on real-time order monitoring and performance evaluation
• Working on a heavy legacy project; improving and fixing it in order to increase modularity, to work as a plugin for the external third-party order management system
• Working on FIX Gateways and Feed Handlers to support different data sources from different markets
• Working as a project lead: defining requirements, organizing development cycles, prioritizing tasks, communicating with clients
• Working as a team lead: mentoring, tracking developers’ progress and empowering younger colleagues

Programming Languages

• Java, JavaScript/TypeScript, Python, C++

Frameworks & Libraries

• Java: Spring Boot, Hibernate
• JavaScript/TypeScript: Node.js, Express.js, Next.js, React, Redux, Angular
• Python: Flask, FastAPI, asyncio
• C++: C++ Actor Framework

Testing Tools

• JUnit/Jupiter, Mockito, Jest, Cypress, unittest

Databases & Caching

• PostgreSQL, Oracle, MongoDB, Redis, Hazelcast

Messaging & Streaming

• Kafka, ActiveMQ Artemis

DevOps & CI/CD

• Docker, Kubernetes, Terraform, Jenkins, Git, GitHub Actions, GitLab CI/CD, AWS

Monitoring & Observability

• Prometheus, Grafana, New Relic

Systems & Scripting

• Linux, Bash

Telecommunications

• Asterisk, FreeSWITCH

Agora center, Tuzla » Volunteer, teacher, trainer, mentor

March 2013 - Present

University of Tuzla, Tuzla » Developer / Contractor

February 2021 - December 2021

• Developing tool for quality estimation at the university
• Defining requirements and scope of the project, working on front-end and back-end sides, deploying and maintaining the complete solution

Faculty of electrical engineering, Tuzla » Teacher assistant

September 2018 - September 2021

• Courses: Data structures and Web design (HTML, CSS and JavaScript)

Pecivo & Kafa, Tuzla » Coffee shop co-owner

February 2016 - November 2016

Faculty of electrical engineering, Tuzla » Master’s degree - Computer Science

September 2018 - Present

Faculty of electrical engineering » Bachelor’s degree - Computer Science

September 2010 - September 2014

For more technical context on me please check my side projects. Most of them are not production ready. All of them are implemented in my free time to explore some concepts or to solve my real-life problems.

Quoter

Simple service for generating random quotes deployed using k8s. Quoter uses ChatGPT and RAG under the hood to generate answers with quotes inside.

Java

Spring Boot

Spring AI

PostgreSQL

OpenAPI

ChatGPT

RAG

Kubernetes

Docker

Pikajia

In Bosnia and Herzegovina we had PIK.ba online marketplace. It was a very primitive and limited marketplace but that is the place where I found the biggest number of my vinyl records. PIK did not have any advanced filters, especially no mechanism to subscribe on changes in filter results. I decided to help myself and developed Pikajia. Pikajia was deployed in AWS (ECR, IAM, Lambda, SQS, S3 and DynamoDB) using Terraform. In the meantime, OLX bought PIK and redesigned the site completely, introducing smart filters and update notifications. Pikajia is now out of service. RIP.

Python

Node.js

TypeScript

AWS

AWS CLI

Terraform

PlantUML

Structurizr (C4)

Bash

Market Agila

My main goal here was to try ksqlDB for tracking changes in the database with the possibility of ETL processing.

Java

Spring Boot

Kafka

Kafka Connect

Debezium

ksqlDB

PostgreSQL

Flyway

WebSocket

Fogg Boutique

I've started this project in order to try async Python and MongoDB change streams. Nice thing about this project is the fact that MongoDB is started as a replica set with a single node, since change streams require replica sets.

Python

FastAPI

asyncio

React

Axios

WebSocket

MongoDB

JWT

Stella

This project demonstrates usage of mentioned technologies to provide telemetry and observability mechanisms.

Java

Spring Boot

Prometheus

Grafana

Loki

Fluent Bit

Docker