Senko Rašić, Developer in Zagreb, Croatia
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Senko Rašić

Verified Expert  in Engineering

Videos Developer

Zagreb, Croatia
Toptal Member Since
August 11, 2017

Senko has over two decades of experience building scalable distributed systems, robust back-end services, and user-facing web applications, and over a decade of experience in leadership positions. Senko specializes in audio/video streaming, web multimedia, and real-time web applications. He's looking for high-impact projects requiring and allowing for reliable, elegant, maintainable, well-written, and tested code.


Good Code
Debian, Ubuntu, Redis, PostgreSQL, Go, Python, Django
Songback (via Toptal)
Streaming, Video on Demand (VOD), Stripe, Django, Vue
Podium Arts (via Toptal)
JavaScript, FFmpeg, Streaming, Wowza




Preferred Environment

Git, ITerm, Sublime Text, MacOS

The most amazing...

...thing I've coded is a complete operating system built on top of L4 microkernels.

Work Experience

Founder | CEO

2010 - PRESENT
Good Code
  • Led a team of software developers on projects for clients all around the world.
  • Analyzed business problems and goals, developed and proposed solutions, and designed the software architecture on dozens of projects.
  • Developed a Python package for an extensive REST API for a cloud-based user management and authentication SaaS startup.
  • Created widely used Python package for inspection and optimization of SQL queries in Django ORM.
  • Designed and implemented music streaming service in Go and the control interface and API for it in Django.
  • Developed and spun-off two internal projects into successful independent startups.
Technologies: Debian, Ubuntu, Redis, PostgreSQL, Go, Python, Django

Freelance Senior Application Architect

2018 - 2019
Songback (via Toptal)
  • Helped the client refine the MVP concept and wrote functional and technical specifications.
  • Analyzed multiple cloud video and payment solutions in the context of project requirements and budget.
  • Designed the architecture for a video platform featuring video on demand, live streaming, and a digital sales and payments platform.
  • Led a team of developers on the project.
  • Built custom integration with a cloud video platform: ingestion, transcoding, delivery, and playback of video-on-demand and live streams.
  • Reverse-engineered and extended a third-party HTML video player with project-specific functionality.
  • Integrated a Stripe Connect platform.
Technologies: Streaming, Video on Demand (VOD), Stripe, Django, Vue

Freelance Lead Software Engineer

2017 - 2018
Podium Arts (via Toptal)
  • Built a web app for monitoring live/dvr video streams and cutting of clips into standalone files.
  • Used HDS and FFmpeg for frame-accurate seeking within the stream and clipping it.
  • Implemented a Wowza streaming engine plugin for clip extraction.
  • Enhanced an existing open-source video player with a zoomable/seekable video editor timeline.
  • Implemented an interface for the organization and management of video clips.
Technologies: JavaScript, FFmpeg, Streaming, Wowza

Software Developer

2006 - 2012
  • Built the message/call storage and notification platform for Nokia N900 smartphones (a Maemo operating system).
  • Rewrote the Jingle (XMPP voice/video call) functionality in Telepathy (the real-time communication software used on all Linux desktops).
  • Contributed to LibJingle—a Google-maintained real-time communication stack that modern WebRTC implementations originate from.
  • Balanced the needs of the open source community and proprietary client needs.
  • Coordinated with the clients on requirements definition and solution architecture and involving the broader open-source community.
Technologies: XMPP, Telepathy, FreeDesktop, GNOME, Linux

Principal | Consultant

2006 - 2010
  • Developed a proprietary distributed video-processing pipeline and storage solution using FFmpeg and associated tools.
  • Wrote live-streaming software that synced the video feed with speaker slides using Adobe's Flex and Live Streaming platforms.
  • Built, as an internal project, the largest news aggregator in Croatia and sold it to the regional media leader.
Technologies: Python, C, Linux

Software Developer

2005 - 2005
  • Researched, designed, and developed a proprietary machine vision system for tracking the movement of a robotic head in a nuclear reactor inspection.
  • Presented the technical challenges and solutions for machine vision in front of the international clients of the company.
Technologies: Computer Vision, C#, C

Web Developer | DevOps

2000 - 2001
Iskon Internet
  • Provisioned and deployed Linux- and Solaris-based services for internal use within the ISP.
  • Implemented a web-based system for job applications for the HR department in Perl.
Technologies: Python, PHP, Perl, Solaris, Linux

MusicBox is a music streaming service focused on cafes, restaurants, hotels, and similar venues where music is an important part of the experience.

For MusicBox, I developed a custom MP3 streaming server in Go—capable of delivering thousands of different music channels on modest hardware. I also developed the Django application that users can use to control the service which communicates with the streaming server using Redis. I automated the deployment of the entire system using Ansible.

On the client-side, I built a Raspberry Pi-based media player that acts as a client for the service with adaptive buffering, offline play, and other important features.

Web Whiteboard

Web Whiteboard is a real-time shared whiteboard service (Google Docs for whiteboards), used by over 200,000 users worldwide each month, from kids in kindergarten to Ivy League schools and Fortune 500 board rooms.

I developed the initial version using Node.js, (WebSockets) and MongoDB. I continued my engagement with the project in the CTO role.

Real Digital Media

I designed and developed a custom digital signage solution that utilized Python-based content players (capable of full or boxed-screen playback of multiple types of content—including 2x HD streams on Nvidia ION hardware), Windows-based content and player management application (C#/WinForms), a RESTful API, and content server.


Naslovnica ("Frontpage") was the largest local news aggregator in Croatia that fetched news articles from dozens of media outlets and presented (the excerpts) in a user-friendly and easy-to-read way.

I developed the site using Python for the back-end and PHP for the front-end and devised an article deduplication algorithm that collated articles from different sites that talked about the same thing.

Ultimately I sold the site to Styria (the leading regional media group).

SQLQ Inspector for Django
A Django application that provides middleware for inspecting and reporting SQL queries executed for each web request.

I built it to help me identify the sub-optimal SQL queries we sometimes generated by mistake or omission. Since open sourcing it, it has become quite popular and widely used.

A lightweight set of tools for implementing JSON-based RESTful APIs in Django. It helps with writing APIs that loosely follow the RESTful paradigm without forcing you to do so and without imposing a full-blown REST framework.

Although these days, I mostly use a Django REST Framework since it's become the de-facto standard way of doing REST in Django, I still maintain (and have uses for and users of) Django-Restless.

L4-Based Microkernel Operating System
A simple educational operating system built on top of the L4 microkernel. I designed and implemented it as part of my graduation thesis.

For the OS, I implemented the memory, namespace, capabilities, disk, filesystem, and console services as well as an ELF loader, and ported a few simple open source tools (tiny basic and scheme interpreters).

Web Camp Zagreb
I co-founded a small community-oriented web developer conference in 2012. The conference grew to be the largest of its kind in the region, visited by over 600 people over two days each year.
1998 - 2006

Master of Science (Diplom-Ingenieur) Degree in Computer Engineering

University of Zagreb—Faculty of Electrical Engineering and Computing - Zagreb, Croatia


FFmpeg, REST APIs, Vue, Stripe


Git, NGINX, Sublime Text, ITerm, GNOME, Wowza


Django, Telepathy


C, Python, Bash Script, JavaScript, Go, C#, Perl, PHP


Linux, Music Streaming, MacOS, Ubuntu, Debian, Solaris


Agile Software Development, Unit Testing, Kanban


PostgreSQL, Redis, MongoDB


Distributed Systems, Team Leadership, Technical Leadership, Videos, Video on Demand (VOD), HTTP Live Streaming (HLS), FreeDesktop, XMPP, Computer Vision, Streaming

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