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Ivan Voras, Open Source Developer in Zagreb, Croatia
Ivan Voras

Open Source Developer in Zagreb, Croatia

Member since August 26, 2014
Ivan is primarily a back-end developer with 18+ years of experience architecting and implementing server-side solutions, including distributed platforms, such as blockchains, chat servers, and game back-ends. He has handled DBA operations, developed modules for PostgreSQL, and has experience developing firmware for IoT devices. He helped establish the Toptal blockchain specialization, served as a tech screener, and lectured for Toptal Academy.
Ivan is now available for hire
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Portfolio

Experience

Location

Zagreb, Croatia

Availability

Part-time

Preferred Environment

VS Code, Go, Git, GCC, Vim Text Editor, Linux, Python, SQLite, Back-end Development, WhatsApp

The most amazing...

...thing I've developed is a blockchain from scratch (github.com/ivoras/daisy).

Employment

  • CTO and Founder

    2019 - PRESENT
    Equinox Vision d.o.o.,
    • Architected and developed a highly scalable back-end architecture to handle hundreds of thousands of users for the global AR platform the company is developing.
    • Assembled a team of developers, designers, and marketers to launch the company as a startup.
    • Managed the startup's founding team for the early stage of the company.
    Technologies: Go, Unity, DevOps, Management, PostgreSQL, HTTP API, Crypto, Scraping, System Architecture, Software Architecture, CTO, API Design, Architecture, Databases, Kubernetes, Back-end Development, Back-end Architecture, API Integration, Technical Leadership, Full-stack, Team Leadership, SaaS, APIs, Augmented Reality (AR), AR Interfaces, RESTful APIs, Financials, Back-end, Scripting, Docker, Docker Compose, Web Security, REST, Scalable Architecture, Due Diligence, Distributed Systems, Puppet, Non-fungible Tokens (NFT)

  • Consultant | Developer

    2015 - PRESENT
    Ideja na kvadrat (Self-employed)
    • Developed the back end for a Bitcoin explorer tool with PostgreSQL, Redis, and Python.
    • Handled DBA and DevOps for large companies and startups.
    • Worked with a self-employment company as a consultant and freelance in web app architecture, big data processing architecture, and high-performance network services.
    Technologies: PostgreSQL, Python, Go, C, Database Design, Django, Blockchain, Cryptography, Web Services, HTTP API, Bitcoin, Cryptocurrency, Ansible, Linux, Security Policies & Procedures, Linux Servers, Amazon S3 (AWS S3), Crypto, ARM, Makefile, CMake, AWS, PCB Design, Scraping, Data, System Architecture, IT Consulting, Cloud, Software Architecture, CTO, MySQL, Technical Writing, API Design, Embedded C, PCB, Microcontrollers, Architecture, Databases, Kubernetes, Flask, Back-end Development, Back-end Architecture, API Integration, Web Development, Technical Leadership, MQTT, Cassandra, Full-stack, Solidity, API Development, Team Leadership, SaaS, APIs, Open Source, RESTful APIs, API Documentation, Back-end, Scripting, Data Pipelines, Apache Kafka, Swagger, Docker, Docker Compose, REST, Blockchain & Cryptocurrency, Ethereum, Decentralized Finance (DeFi), Ethereum Smart Contracts, Software Design, Scalable Architecture, Web Scraping, Data Engineering, Distributed Systems, Container Orchestration, Non-fungible Tokens (NFT)

  • Open Source Developer

    2000 - PRESENT
    Freelance
    • Authored dozens of open source projects, including applications and libraries.
    • Created a faster, faster, high-performance memory cache server with more features than Memcached.
    • Built a module for PostgreSQL (written in C) to extend the full-text-search facility with support for the Croatian language.
    • Developed a module for PostgreSQL (written in C) to support on-the-fly.
    • Created a client-side public key encryption module in JavaScript and PHP for secure user authentication without SSL.
    • Developed a fixed-point header library in C for environments without floating-point support (e.g., embedded).
    • Created an encrypted notepad app for desktop and Android editing, directly saving encrypted files.
    • Updated a blog regularly at http://ivoras.net/blog/tree/.
    Technologies: Java, PHP, Python, C++, C, Database Design, System Administration, Embedded Software, Bitcoin, Cryptocurrency, Linux, Crypto, Android, System Architecture, IT Consulting, Software Architecture, MySQL, Technical Writing, API Design, Django, Architecture, Databases, GDB, Valgrind, Back-end Development, Back-end Architecture, API Integration, SaaS, APIs, Open Source, RESTful APIs, API Documentation, Back-end, Scripting, HTML, Apache Kafka, Swagger, Docker, Docker Compose, REST, Microservices, Blockchain & Cryptocurrency, Smart Contracts, Software Design, Distributed Systems, Container Orchestration

  • Senior Lead PHP Developer

    2016 - 2021
    Foothold Technology, Inc.
    • Troubleshot performance issues and daily database issues for a large web app.
    • Worked with and consulted the DevOps team in closing hard-to-catch issues relating to the Linux kernel and PostgreSQL internals.
    • Participated in planning and designing sysadmin/ops activities and requirements.
    • Managed a data processing pipeline using Airflow and Snowflake.
    Technologies: PHP, SQL, Zend Framework, Angular, PostgreSQL, AngularJS, Ajax, Snowflake, Embedded Software, System Architecture, IT Consulting, Amazon Web Services (AWS), Software Architecture, Architecture, Databases, Back-end Development, Back-end Architecture, Web Development, Technical Leadership, Full-stack, Data Pipelines, Web Security, REST, JavaScript, CSS, HTML5, Data Science, Scalable Architecture, Data Engineering

  • C Developer

    2015 - 2018
    EvoBits Information Technology SRL
    • Developed the back end for a blockchain explorer product using Python and PostgreSQL.
    • Created a system that periodically imports blockchain data into PostgreSQL for analytics purposes.
    • Developed forks of the Bitcoin codebase to work as altcoins.
    Technologies: C, Bitcoin, Extreme Programming, Unit Testing, CentOS, Bash, Python, Bitcoind, IT Consulting, Back-end Development, Back-end Architecture, REST, Blockchain & Cryptocurrency, Smart Contracts, Software Design, Distributed Systems, C++, Puppet

  • CTO and Founder

    2014 - 2016
    Akira Industries
    • Developed multiple iterations of a PCB board for an IoT product.
    • Assembled and tested pre-production PCB boards and made them ready for production.
    • Managed PCB manufacture and assembly of pre-production PCB samples with a Chinese manufacturer (JLCPCB).
    Technologies: Electronics, Digital Electronics, PCB Design, CTO, Embedded C, PCB, Microcontrollers, Architecture, Back-end Development, Back-end Architecture, Renewable Energy, Technical Leadership, Team Leadership, REST, Software Design, Container Orchestration, Puppet

  • Kernel Developer

    2007 - 2015
    FreeBSD
    • Wrote kernel-side code dealing with storage systems (GEOM).
    • Designed and implemented a device-level journaling module.
    • Designed and implemented a virtual storage module.
    • Gave talks at annual FreeBSD conferences about my work with storage systems (GEOM).
    • Participated in the vibrant international community of users and developers.
    Technologies: C, SQLite, FreeBSD, System Architecture, Software Architecture, API Design, GDB, Valgrind, API Development, RESTful APIs, API Documentation, Back-end, Scalable Architecture, C++

  • Internet Services Architect

    2001 - 2015
    University of Zagreb
    • Designed and implemented the core of a web content management system back when they were a new concept (2001-2002).
    • Designed the faculty web and student information systems as a technology and product architect.
    • Designed a very modular web application framework.
    • Designed and optimized the design of the database to include recent PostgreSQL features.
    • Designed and implemented the server-side environment based on FreeBSD for high performance and uptime.
    • Spearheaded the implementation of new technologies into existing products and processes.
    • Completed a PhD in an efficient multithreaded client-server architecture.
    Technologies: PostgreSQL, PHP, Database Design, System Administration, Security Policies & Procedures, Architecture, Back-end Development, Back-end Architecture, Technical Leadership, API Development, Team Leadership, Open Source, Web Security, REST, JavaScript, CSS, HTML5, Software Design, Scalable Architecture

Experience

  • Daisy Blockchain
    https://github.com/ivoras/daisy

    A private blockchain where blocks are SQLite databases, in Go.

  • ESP8266 3LED
    https://easyeda.com/84e3e8ee/ESP8266_3LED_1_3-9442fb3e6844443299208137daf8dcda

    An IoT board around ESP-12S module (with ESP8266) powered by a 9V-18V DC jack, with three signaling WS2812 LEDs, two buttons, an OLED display, a beeper, and a temperature and humidity sensor. The board is meant to act as a hub and connect to other devices with more sensors.

  • Bullet Cache

    A memory cache server faster than Memcached (in its timeframe) and with more features, such as cache record tagging and tagged expiry. It also has more flexible operations on multiple cached items.

  • My Electronics Blog
    http://ivoras-electronics.tumblr.com/

    Since late 2015, I've been doing an increasing amount of work with Arduinos and similar-style electronics. I've created a blog to share what I've learned and to learn from the comments!

    I'm currently interested in low-power design and solar power.

  • Working with ESP32 Audio Sampling (Publication)
    https://www.toptal.com/embedded/esp32-audio-sampling
    The successor of the revolutionary ESP8266, the ESP32 is a next-generation microcontroller. Find out how to sample its analog-to-digital converter (ADC) from a timer interrupt using the Arduino IDE.
  • Guide to Multi-processing Network Server Models (Publication)
    https://www.toptal.com/software/guide-to-multi-processing-network-server-models
    In this article, Toptal engineer Ivan Voras provides a useful overview and comparison of multi-processing network server models, with the goal being to take some of the mystery out of writing high performance networking code. The article is intended for "system programmers", i.e., back-end developers who will work with the low-level details of their applications, implementing network server code.
  • Software Development Anywhere: My Distributed Remote Workplace (Publication)
    https://www.toptal.com/remote/software-development-anywhere-my-distributed-remote-workplace
    Working as a remote software development freelancer has many benefits, but setting up an effective distributed working environment can be a real challenge. In this article, Toptal Engineer Ivan Voras describes how he leverages SSH and a number of related technologies, along with the Raspberry Pi and ownCloud, to be able to work effectively from anywhere.
  • Installing Django on IIS: A Step-by-Step Tutorial (Publication)
    https://www.toptal.com/django/installing-django-on-iis-a-step-by-step-tutorial
    Although the most wide-spread and supported way of running Django is on a Linux system (e.g., with uwsgi and nginx), it actually doesn't take much work to get it to run on IIS. In this article, Toptal Engineer Ivan Voras walks you through a step-by-step tutorial, clearly explaining how to install Django on IIS.

Skills

  • Languages

    Go, SQL, Python, C, Snowflake, Stored Procedure, Regex, PL/pgSQL, Embedded C, Solidity, PHP, Java, Bash, HTML, JavaScript, CSS, HTML5, C++

  • Frameworks

    Django, Knockout (Knockout.js), Flask, Bootstrap, Swagger, Unity3D, Unity

  • Libraries/APIs

    API Development, LibC, Sockets, HTTP API, POSIX, Arduino RTC, Python Imaging Library, LocalStorage, AES, Puppet.js, Social APIs, Pygame, FFmpeg, SDL, Google API, pcap, ZeroMQ

  • Tools

    Ansible, PuTTY, Vim Text Editor, Git, Apache, GitHub, Django-admin-tools, Trac, Subversion (SVN), Bitbucket, KVM/Qemu, NGINX, Mercurial, SQL Prompt, VirtualBox, Makefile, CMake, Valgrind, MQTT, Docker Compose, Puppet, VS Code, Apache Airflow, Postfix, Notepad++, MediaWiki, HSQLDB, cURL Command Line Tool, Trello, GCC, VPN, GDB

  • Paradigms

    Concurrent Programming, Back-end Architecture, Database Design, REST, Object-oriented Programming (OOP), DevOps, Socket Programming, Microservices, Real-time Systems, High-performance Computing, Refactoring, Clean Code, Data-driven Programming, Object-oriented Design (OOD), Management, Unit Testing, Data Science

  • Platforms

    Blockchain, Ubuntu, Linux, LAMP, Raspberry Pi, BSD, Red Hat Linux, Debian Linux, CentOS 6, CentOS, Kubuntu Linux, Linux RHEL/CentOS, Unix, FreeBSD, Docker, Ethereum, Xen, Django CMS, Android, Raspbian, Kernel Programming, Keychain, Arduino, Amazon Web Services (AWS), Kubernetes, Apache Kafka

  • Storage

    PostgreSQL, Database Performance, SQLite, Memcached, Cache, FlatFile, Database Administration (DBA), Databases, SQL Stored Procedures, Database Modeling, NoSQL, LevelDB, DB, Redis, smbd, MySQL, Amazon S3 (AWS S3), Data Pipelines, Cassandra, SQL Performance, MySQL Daemon, Internal Databases, Database Replication, JSON, Apache Derby, Firebird, LVM, CouchDB, Berkeley DB, MongoDB

  • Other

    Performance Tuning, Software Architecture, Cryptocurrency, Cryptocurrency Development, Architecture, Version Control, TCP/IP, SSL, Bitcoind, Back-end Development, System Architecture, HTTP, Open Source, Bitcoin, System Administration, SSH, Memory Mapped Files, IT Consulting, Software Engineering, Linux Servers, Data, CTO, Technical Writing, API Design, API Integration, Web Development, Technical Leadership, SaaS, APIs, RESTful APIs, API Documentation, Back-end, Scripting, self-hosting, Software Design, Scalable Architecture, Game Back-end, Documentation, White Papers, Security Policies & Procedures, ESP8266, Hardware, Electronics, Firmware, Network Programming, WebSockets, Bluetooth, Distributed File Systems, Cryptography, Ethernet, Networks, Web Services, UDP, Encryption, TCP, Embedded Systems, Site Speed Optimization, Public-key Cryptography, SMTP, SFTP, FTP, GNU, Unix/Linux Virtualization, RSync, Multithreading, Writing & Editing, iSCSI, Hash, Regular Expressions, HTTP Server, Data Structures, Prototyping, Embedded Software, Crypto, Cryptocurrency APIs, Blockchain & Cryptocurrency, Scraping, Cloud, Team Leadership, Augmented Reality (AR), AR Interfaces, Web Security, WhatsApp, Smart Contracts, Decentralized Finance (DeFi), Ethereum Smart Contracts, Web Scraping, Data Engineering, Distributed Systems, Container Orchestration, Non-fungible Tokens (NFT), Data Warehousing, Data Warehouse Design, Consulting, Digital Electronics, Algorithms, ARM Embedded, Apache Cassandra, Electrical Engineering, System Design, NFS, IMAP, Unix Shell Scripting, Genetic Algorithms, RPC, Memory Profiling, Social Media Integration, Single Sign-on (SSO), Protocol Buffers, RSA, OAuth, Peer-to-peer Networking, Lean Development, Embedded Hardware, Software Consulting, Technical Consulting, ARM, AWS, PCB Design, PCB, Microcontrollers, Renewable Energy, Full-stack, Financials, Due Diligence

Education

  • PhD Degree in Computer Engineering
    2006 - 2011
    University of Zagreb - Croatia

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