Milorad Kalezic, Developer in Podgorica, Podgorica Municipality, Montenegro
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Milorad Kalezic

Verified Expert  in Engineering

Software Developer

Podgorica, Podgorica Municipality, Montenegro
Toptal Member Since
December 24, 2019

Milorad has over 15 years of experience in the maintenance and development of system software and great working knowledge in a variety of system environments. With attention to details and strong analytical skills, he provides creative and innovative solutions to the most complex problems. He's dedicated and enthusiastic, focuses on concise and articulate communication, and strives to complete all assignments to the highest standard.


VoiceNation LLC
Amazon Web Services (AWS), Cloud Migration, Linux
Lariat Data, Inc.
Terraform, Python, Docker, Amazon Web Services (AWS), DevOps, Documentation
Visibly Works LLC
Amazon Web Services (AWS), PostgreSQL, Python, AWS Lambda, eCommerce, ECS...




Preferred Environment

KVM, Amazon Web Services (AWS), Elastic, Docker, Terraform, Jenkins, PHP, MySQL, Linux

The most amazing...

...thing I've developed was an application used as EC2, RDS, ES, S3, IAM, and SG inventory for the corporation with 200+ AWS accounts.

Work Experience

AWS Engineer

2023 - 2023
VoiceNation LLC
  • Helped the VoiceNation engineering team migrate their infra from the local data center to AWS.
  • Helped the VoiceNation engineering team migrate from the older MySQL database version to the most recent MariaDB database version with a master-replica setup.
  • Worked with the VoiceNation engineering team to aggregate multiple relay mail servers to use a centralized AWS SES solution.
Technologies: Amazon Web Services (AWS), Cloud Migration, Linux

AWS DevOps and Infrastructure Engineer

2023 - 2023
Lariat Data, Inc.
  • Bootstrapped AWS infrastructure using Terraform, used for secure sharing credentials with the customer via KMS and later deployment of the product modules in customers' AWS accounts.
  • Automated the deployment of the product module in customers' accounts using Docker-based Lambda and Terraform.
  • Used GitHub Actions to create CI/CD pipelines for creating, tagging, and pushing ECR images used by Lambda.
Technologies: Terraform, Python, Docker, Amazon Web Services (AWS), DevOps, Documentation

DevOps Engineer

2021 - 2022
Visibly Works LLC
  • Migrated deployment of existing infrastructure components from CloudFormation to Terraform and configured new infrastructure deployment procedures for multi-tenant or shared and single-tenant or private clouds.
  • Enabled automatic tracking and notification for multiple AWS services, including ECS, EC2, DocumentDB, OpenSearch, SQS, SNS, Lambda, CloudFront, S3, CloudTrail, CodeDeploy, and CodePipeline.
  • Configured EC2 instance templates using Packer for the development team to have uniform development servers with the latest software.
  • Fulfilled all AWS infrastructure requirements for SOC 2 audit.
Technologies: Amazon Web Services (AWS), PostgreSQL, Python, AWS Lambda, eCommerce, ECS, Advertising Technology (Adtech), Amazon S3 (AWS S3), Amazon EC2

Senior DevOps Engineer

2021 - 2022
Flightdeck Virtual Meetings Ltd
  • Migrated from Azure to AWS and improved the infrastructure design for the product.
  • Automated the deployment of infrastructure components with Terraform.
  • Conducted simulations of 10,000 concurrent users on Livve remote video streaming event.
Technologies: DevOps, MySQL, Python, Amazon Web Services (AWS), Kubernetes, Docker, Google Cloud, Apache Tomcat

DevOps Engineer

2020 - 2021
Formulus Black Corporation
  • Configured a mechanism for network isolation of in-memory virtual machines on multi-tenant VM hosts, with auto-provision of a new host in case of need for more host resources.
  • Prepared various virtual machine templates for multiple operating systems for the product.
  • Enabled mechanism to back up and restore virtual machines from in-memory to S3 and vice versa.
Technologies: Linux, JavaScript, DevOps, Virtualization

Senior Cloud Operations Engineer

2019 - 2019
  • Developed an application that tracks if any of the public IP addresses from 200+ AWS accounts was blacklisted on some global SMTP blacklist.
  • Worked on incident resolutions for 30+ projects in the company's portfolio.
  • Worked on deployments of new release versions on numerous occasions.
Technologies: System Administration, Linux Administration, Amazon Web Services (AWS), Ansible, PostgreSQL, Oracle, Microsoft SQL Server, MySQL, Windows, Linux, VMware, Kubernetes, Docker

Security Analyst

2017 - 2019
  • Developed an application used as EC2, RDS, ES, S3, IAM, and SG inventory for 200+ AWS accounts.
  • Performed quarterly scans of 11,000+ private and public IP addresses, 100+ web applications, and 10,000+ Docker images.
  • Executed daily checks of AD activities, OSSEC logs, VPN logs, VPC flow logs, and suspicious CloudTrail activities.
Technologies: System Administration, Linux Administration, Amazon Web Services (AWS), Twistlock, Nessus, QualysGuard, Windows, Linux, VMware, Kubernetes, Docker

Monitoring Specialist

2016 - 2017
  • Implemented various monitoring checks for numerous services or hosts.
  • Developed Selenium-based web monitoring checks, which replaced existing New Relic checks.
  • Integrated monitoring alerts with the proper Jira tasks and Slack notifications.
Technologies: System Administration, Linux Administration, Jira, PagerDuty, Docker, New Relic, Selenium, Amazon CloudWatch, Telegraf, Grafana, Prometheus

SaaSOps and Network Engineer

2014 - 2016
  • Deployed new software releases for multiple products on a weekly basis.
  • Maintained a corporate active directory of 5,000+ users and VPN servers daily.
  • Served as an L2 support on reported Jira requests and incidents.
  • Maintained corporate Jira and Confluence servers on a daily basis.
Technologies: System Administration, Linux Administration, Amazon Web Services (AWS), Azure Active Directory, Zendesk, Jira, Subversion (SVN), Git, SoftEther VPN, OpenVPN, SaaS Operations (SaaSOps)

System Engineer

2009 - 2014
  • Acted as the head of the operations and maintenance department.
  • Developed, tested, and maintained multiple products, including a mail platform for OpenMX, an authorization and billing platform for telecommunication for OpenProvider, and a network firewall and VPN concentrator for LagWall.
  • Contributed to the implementation of Asterisk PBXs in multiple locations.
  • Served as the Cisco assistant and network engineer for banking clients.
  • Contributed to numerous implementations of Xen Virtualization.
Technologies: System Administration, Linux Administration, Apache Tomcat, NGINX, Apache, Java, Asterisk, Nagios, Postfix, Qmail, Linux, Xen, PHP, MySQL

Chief Specialist for Operations and Maintenance of IP Services

2006 - 2009
Crnogorski Telekom
  • Maintained corporate core services such as mail, authorization and billing, web hosting, IPTV, and monitoring.
  • Developed internally used real-time applications to monitor the IPTV channels.
  • Implemented Nagios monitoring checks on multiple services.
  • Deployed numerous versions of different product releases and participated in many team collaborations in similar efforts.
Technologies: System Administration, Linux Administration, Nagios, Qmail, Cisco, PHP, MySQL, Linux


This project represents EC2, RDS, ES, S3, IAM, and SG inventory for multiple AWS accounts. It also includes the other modules that show the possible flows in the configuration of DNS records for the corporate domains, public GitHub repositories that are tied to the organization and AD groups with 0 members or without a maintainer.

SMTP Blacklist Checks for all Corporate Public IP Addresses

This solution performed daily checks if any of the corporate public IP addresses (from multiple AWS accounts and dedicated VMWare servers) were listed in some of the public global SMTP Blacklists. This feature was mainly used when Elastic IPs were compromised before in some Amazon account, and later released and tied to the dedicated Docker hosts.

Scheduler for Starting and Stopping of Amazon EC2 Instances

This project was used as an in-house solution for automatic stopping and starting of EC2 instances, which didn't need to be active all the time (Dev, QA, and Staging instances). The main goal of this project was to reduce costs in AWS accounts. As an additional feature, this project had the option of scheduled creation of AMIs, as well.
2010 - 2012

Master's Degree in Computer Science and Bioinformatics

University of Montenegro - Podgorica, Montenegro

2000 - 2005

Bachelor's Degree with Honors in Electrical Engineering and Computing

University of Montenegro - Podgorica, Montenegro


Terraform, Nessus, VMware, Graylog, Jenkins, Ansible, Grafana, Elastic, Twistlock, Telegraf, Amazon CloudWatch, Jira, Postfix, Nagios, Asterisk, Apache, NGINX, Apache Tomcat, OpenVPN, SoftEther VPN, Git, Subversion (SVN), Splunk


PHP 7, PHP, Java, Python, JavaScript


Linux, QualysGuard, Amazon Web Services (AWS), LAMP, Docker, Windows, Oracle, New Relic, PagerDuty, Xen, Zendesk, KVM, Kubernetes, AWS Lambda, Amazon EC2




MySQL, Microsoft SQL Server, Azure Active Directory, PostgreSQL, Google Cloud, Amazon S3 (AWS S3)




Linux Administration, System Administration, Prometheus, Qmail, Cisco, eCommerce, ECS, Advertising Technology (Adtech), Virtualization, Documentation, Cloud Migration, SaaS Operations (SaaSOps)

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