Porin Custic, Developer in Zagreb, Croatia
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Porin Custic

Verified Expert  in Engineering

Software Developer

Location
Zagreb, Croatia
Toptal Member Since
March 18, 2020

Porin is a seasoned software engineer specializing in the development of distributed, highly-scalable systems. With hands-on experience managing large-scale applications that handle hundreds of millions of customer requests daily and sustainably process over a billion database records, his expertise stands unparalleled. Using his background in mathematics and theoretical computer science, Porin not only delves deep into a wide range of topics but also consistently delivers top-tier code.

Portfolio

Insomniac Design Inc
Python, FastAPI, REST APIs, PostgreSQL, Google Cloud Platform (GCP), SQLAlchemy...
Lyrasis
Python, Flask, Django, Python 3, Pytest, PostgreSQL, Amazon Web Services (AWS)...
Rhapsody - Main
Python, Google Cloud Platform (GCP), Pytest, MongoDB, Video Streaming, Audio...

Experience

Availability

Part-time

Preferred Environment

Docker, Python, GitLab, GitHub, Trello, Jira, PyCharm, Skype, Slack, Linux

The most amazing...

...thing I've developed is an API that was crucial for my current company to close a large deal with a new customer (a major name in the IT industry).

Work Experience

Back-end Python Developer

2023 - 2023
Insomniac Design Inc
  • Worked on developing a FastAPI-based application for managing, exploring, and presenting environmental data. It was showcased to and praised by multiple world leaders.
  • Implemented role-based authentication in the FastAPI application that supported users in the local database and the external Firebase system. It increased the security and flexibility of the application.
  • Improved the security of the application by implementing and improving several parts of the user authentication system like password history check, password validation check, disabling users on specific actions, and others.
  • Fixed bugs and developed features that helped the team deliver the application with a tight deadline to showcase at the biggest environmental conference in the world.
Technologies: Python, FastAPI, REST APIs, PostgreSQL, Google Cloud Platform (GCP), SQLAlchemy, Docker, Redis, Firebase, Firebase Web SDK, Alembic, Pandas, Poetry, Cloud, Object-oriented Programming (OOP), Serverless, XLSX File Processing, Critical Thinking

Senior Python Developer

2022 - 2023
Lyrasis
  • Introduced a self-serve password reset feature in the library management system, eliminating the need for librarians and admins to rely on customer support.
  • Enhanced the library card management application with a GIS API integration, streamlining location input and editing processes.
  • Achieved a significant 600% increase in Mypy type checking coverage, reinforcing code quality.
  • Improved the library card application's security by adopting industry-leading practices and patching known vulnerabilities.
  • Added new features, fixed bugs, and maintained code for the library, ebooks, and virtual library card applications.
Technologies: Python, Flask, Django, Python 3, Pytest, PostgreSQL, Amazon Web Services (AWS), APIs, JavaScript, Ajax, Mypy, Elasticsearch, Back-end, Docker Compose, Unit Testing, Git, Back-end Development, AWS Lambda, Amazon EC2, SQLAlchemy, Pydantic, Automation, Cloud Deployment, System Architecture, Web Servers, Cloud Architecture, REST, Terraform, Amazon DynamoDB, Back-end Architecture, Geospatial Data, Deployment, Integration, JSON, XML, Software Architecture, Third-party APIs, Celery, Cloud, Django REST Framework, Object-oriented Programming (OOP), Inventory Management, Serverless, Critical Thinking

Python Back-end Engineer

2021 - 2022
Rhapsody - Main
  • Migrated parts of a music content streaming platform's old monolith Java-based code to Python microservice architecture.
  • Migrated old Oracle DB schemas to MongoDB to increase the content streaming platform's flexibility.
  • Increased the new microservice platform's unit test coverage by 20%.
Technologies: Python, Google Cloud Platform (GCP), Pytest, MongoDB, Video Streaming, Audio, Microservices, RESTful Microservices, REST APIs, Back-end, Message Queues, DocumentDB, Unit Testing, Git, FastAPI, Back-end Development, Amazon EC2, Automation, System Architecture, Web Servers, Cloud Architecture, Enterprise Architecture, REST, Back-end Architecture, Integration, Full-stack Development, JSON, XML, Software Architecture, Third-party APIs, Cloud, Object-oriented Programming (OOP), Serverless, Critical Thinking

Software Architect

2021 - 2022
Freelance
  • Designed and developed a full-stack application for an early-stage HR startup from the ground up. The application was written in Django and used PostgreSQL as a database layer.
  • Set up the whole infrastructure on a Google Kubernetes Engine with PostgreSQL and Google Cloud Storage. Deployed a Django application to the infrastructure.
  • Created a CI/CD process for testing and automatic deployment of the Django application using GitHub Actions.
  • Wrote and deployed multiple cron jobs on the Google Kubernetes Engine.
  • Created a Slack bot in Python and integrated it with the Django application.
  • Developed the front-end part of the application using JavaScript, jQuery, Chart.js, HTML5, and CSS.
Technologies: Django, Django ORM, Python, Python 3, Docker, Kubernetes, Google Kubernetes Engine (GKE), Google Cloud, Google Cloud Storage, PostgreSQL, uWSGI, JavaScript, HTML, jQuery, Bootstrap, Slack, Slack API, Cron, Chart.js, SCSS, Back-end, Unit Testing, Bots, Git, Back-end Development, CSV File Processing, Automation, Cloud Deployment, System Architecture, Web Servers, Cloud Architecture, REST, Back-end Architecture, Data Analysis, Deployment, Integration, Full-stack Development, JSON, XML, Software Architecture, Third-party APIs, Data Scraping, Webhooks, Celery, CSS, Cloud, WebSockets, Object-oriented Programming (OOP), Chatbots, Critical Thinking

Full-stack Engineer

2021 - 2021
Clarium, Inc.
  • Contributed to a project for a startup in the healthcare industry. Architected and developed the whole back-end system using Python and Flask.
  • Integrated PostgreSQL as a database layer to the Python Flask application.
  • Deployed the Flask application to the Amazon Elastic Container Service (ECS) and integrated continuous deployment with GitHub Actions.
  • Integrated the Auth0 authorization back end for the Python Flask application to support all of the healthcare application's needs.
Technologies: Python, SQL, REST APIs, Amazon Web Services (AWS), RESTful Development, API Architecture, JavaScript, Snowflake, ETL, React, Back-end, DocumentDB, Unit Testing, Git, Back-end Development, Amazon EC2, Automation, Cloud Deployment, System Architecture, Web Servers, REST, Back-end Architecture, Integration, JSON, XML, Third-party APIs, Cloud, Object-oriented Programming (OOP), Critical Thinking

Back-end Developer

2020 - 2020
Exodus Intelligence, LLC
  • Migrated the Python Flask application from PostgreSQL to MongoDB, which increased the application's flexibility and accelerated the development of new features.
  • Developed new features and improved old parts of the code of the Python Flask application that is used by a large portion of IT security researchers.
  • Migrated the Python Flask application from Python 2 to Python 3, which increased security, modernized the application, and decreased technical debt.
Technologies: Python, REST APIs, Flask, React, Full-stack, Python 2, Python 3, PostgreSQL, MongoDB, Amazon Web Services (AWS), Back-end, Git, Back-end Development, Cloud Deployment, System Architecture, Web Servers, REST, Back-end Architecture, JSON, XML, Third-party APIs, Cloud, Object-oriented Programming (OOP), Critical Thinking

Back-end Developer

2017 - 2020
ReversingLabs
  • Designed and developed a high throughput POC for serving files backed by MongoDB.
  • Migrated parts of the back-end system from an in-house developed NoSQL database to ScyllaDB.
  • Developed and monitored a procedure for the transition of 1 PB of files from the old storage system to the new low-latency and high-availability system.
  • Maintained and further improved the API access management system.
  • Improved application monitoring, logging, and error-tracking systems.
  • Designed and developed APIs that handled several million customer requests per day.
  • Participated in the preparation and execution of deployment of back-end architecture on the Docker Swarm platform.
  • Helped with the incident response of the back-end system that consistently had 99.99% availability.
  • Mentored student interns and helped onboard new team members.
Technologies: Solution Architecture, Web Development, Databases, Architecture, API Integration, Algorithms, Trello, PyCharm, NGINX, Kanban, HTML, Docker Swarm, APIs, Jira, Kubernetes, jQuery, MySQL, HTML5, SQL, Amazon Web Services (AWS), GitHub, Microservices, REST APIs, Distributed Systems, ScyllaDB, PostgreSQL, MongoDB, InfluxDB, NoSQL, RabbitMQ, Docker, Linux, Flask, Python, Python 2, Back-end, Message Queues, Docker Compose, Git, Web Scraping, Amazon EC2, Cloud Deployment, System Architecture, Web Servers, Enterprise Architecture, REST, Back-end Architecture, Data Analysis, Deployment, JSON, XML, Third-party APIs, Data Scraping, Cloud, Object-oriented Programming (OOP), Beautiful Soup, Critical Thinking

Student Intern

2016 - 2017
ReversingLabs
  • Tested customer-facing APIs that served over 200 million requests per day.
  • Documented a procedure for adding a new AV scanner to the company's file scanning system.
  • Fixed bugs on several back-end services and APIs written in Python.
  • Checked and fixed the documentation for all customer-facing APIs.
Technologies: Web Development, Databases, API Integration, Algorithms, Trello, PyCharm, NGINX, Kanban, HTML, Docker Swarm, InfluxDB, APIs, Jira, ScyllaDB, MySQL, HTML5, SQL, PostgreSQL, Amazon Web Services (AWS), MongoDB, GitHub, Docker, Microservices, REST APIs, Distributed Systems, NoSQL, RabbitMQ, Linux, Flask, Python, Python 2, Back-end, Message Queues, Git, Back-end Development, Cloud, Object-oriented Programming (OOP)

Summer Student Intern

2015 - 2015
Ericsson Nikola Tesla
  • Worked on a project called concept parametrization as part of the summer camp program.
  • Used a combination of image processing and machine learning techniques.
  • Built a prototype application for concept parametrization of fruit images using Python, OpenCV, and R language.
Technologies: API Integration, Algorithms, APIs, Linux, R, OpenCV, Python

Django Full-stack Web Application

I designed, developed and deployed the full-stack web application for an early-stage startup. It was written in Django (Python), deployed on Google Kubernetes Engine and used PostgreSQL through Django ORM. I used the Bootstrap library on the front-end combined with HTML, JavaScript, jQuery and CSS. A Slack Bot was also created as a part of the project and integrated with a Django application. It enabled multiple points of connection with the application. Alongside the application, there were also several cron jobs written in Python and deployed on GKE. I was the sole developer working on the project.

Back-end System for an Up-and-coming Healthcare Startup

I designed and developed the backend system for a new healthcare startup based in New York City. It consisted of a Flask backend application deployed on the AWS ECS system and used PostgreSQL as a database layer. The app processed, saved and served data connected to hospital expenses and projected costs. The back-end was connected to front-end application, which was written in React. I was part of a two person engineering team and was a sole backend developer.

Files Serving a Back-end System Using MongoDB

I designed and developed a back-end system for files uploading and downloading using Python and MongoDB. It consisted of high throughput files storage servers and a MongoDB database that held the files' metadata. It supported more than 5 million daily writes and more than 30 million daily reads to the database.

Migration of a Back-end Subsystem to ScyllaDB

I prepared, developed, and executed a migration of a distributed back-end subsystem from an in-house developed NoSQL database to ScyllaDB. The migration consisted of developing a new microservice—making changes to several existing ones and coordinating the = deployment so that migration could be carried out without downtime.
Technologies: Python, ScyllaDB, RabbitMQ, NoSQL

First Aid Android App

https://github.com/pcustic/PrvaPomoc
Together with a colleague, I developed an Android mobile application for first aid. It was developed with the help of the Croatian Red Cross, and it consisted of all standard first aid procedures with photos, animations, and audio explanations accompanying it. The app was built as an assistant in providing first aid in stressful emergencies.

Languages

Python 2, Python, SQL, XML, JavaScript, HTML, HTML5, CSS, R, Python 3, C++, SCSS, Snowflake

Frameworks

Django, Flask, Django REST Framework, Bootstrap, Alembic

Libraries/APIs

REST APIs, SQLAlchemy, jQuery, Beautiful Soup, OpenCV, React, Django ORM, Slack API, Google APIs, Chart.js, Mypy, Firebase Web SDK, Pandas

Tools

Slack, Skype, Trello, GitHub, Git, PyCharm, Jira, RabbitMQ, Docker Swarm, GitLab, Docker Compose, Celery, Pytest, Travis CI, Amazon Elastic Container Service (Amazon ECS), NGINX, Auth0, uWSGI, Google Kubernetes Engine (GKE), Cron, Terraform

Paradigms

RESTful Development, Microservices, Kanban, Automation, REST, Back-end Architecture, Object-oriented Programming (OOP), Unit Testing, API Architecture, ETL

Storage

Databases, NoSQL, MongoDB, JSON, PostgreSQL, InfluxDB, MySQL, SQLite, Cloud Deployment, Redis, ScyllaDB, Google Cloud, Google Cloud Storage, Elasticsearch, Amazon DynamoDB

Other

Algorithms, API Integration, Architecture, Web Development, Solution Architecture, Distributed Systems, APIs, Back-end, Message Queues, Back-end Development, System Architecture, Web Servers, Enterprise Architecture, Third-party APIs, Inventory Management, Critical Thinking, Full-stack, Bots, FastAPI, Web Scraping, Pydantic, CSV File Processing, Cloud Architecture, Cloud, Data Analysis, Deployment, Integration, Full-stack Development, Software Architecture, Data Scraping, Webhooks, WebSockets, Chatbots, Serverless, DocumentDB, Security, Nomad, GitHub Actions, CI/CD Pipelines, Slackbot, Slack App, SSL Certificates, HTTPS, Ajax, Video Streaming, Audio, RESTful Microservices, ChatGPT, Geospatial Data, Poetry, XLSX File Processing

Platforms

Amazon Web Services (AWS), Linux, Docker, Google Cloud Platform (GCP), Kubernetes, Django CMS, AWS Lambda, Amazon EC2, Firebase

2015 - 2017

Master's Degree in Computer Science and Mathematics

University of Zagreb - Zagreb, Croatia

2012 - 2015

Bachelor's Degree in Mathematics

University of Zagreb - Zagreb, Croatia

APRIL 2020 - PRESENT

Docker Deep Dive

Linux Academy

OCTOBER 2019 - PRESENT

Google Cloud Concepts

Linux Academy

AUGUST 2019 - PRESENT

MongoDB Basics

MongoDB, Inc.

NOVEMBER 2015 - PRESENT

Algorithms: Design and Analysis, Part 1

Stanford University via Coursera

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