Josef Zamrzla

Josef Zamrzla

Web and mobile applications developer

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I'm a web application/distributed systems developer. I prefer Javascript (Node.js) and/or Python. I have a broad experience using a wide range of data stores, from classic relational SQL databases to key/value and document stores to the full-text engines like ElasticSearch or Fast ESP.

I also offer consultancy in the fields of:

  • architecture and design of distributed systems with an emphasis on ability to handle large loads and flexible horizontal scalability
  • architecture and design of service-oriented systems
  • troubleshooting with performance of Node.js applications (high memory/processor-intensive apps, memory leaks)
  • Javascript applications development and others

Recent projects


Fullstack web applications development.

Technology: Node.js, React, Redux, MobX


Internal web (intranet) applications development (fullstack).

Technology: Node.js, MySQL, Angular (Typescript), React/Redux, MongoDB


Development of payment gateway application that accepts both one-off and recurring payments via Recurly application. Communication with Recurly API and Salesforce API.

Technology: Node.js (Coffeescript), React, MongoDB, Redis, PostgreSQL, RabbitMQ

Develoment of distributed application for analysis and content publication on social networks. Profiling of Node.js apps, solving problems with high CPU and memory consumption of Node.js apps, detecting and managing memory leaks, garbage collection optimalizations.

Technology: Node.js (Coffeescript, ES6), Elasticsearch, MongoDB, Redis, PostgreSQL, RabbitMQ, Websockets

Angelcam (Click2stream)

Design and development of high scalable, fault tolerant, service oriented platform for live video streaming from surveillance cameras. Development od docekerized microservices with service discovery option. Profiling of Node.js apps, solving problems with hign CPU and memory consumption of Node.js apps, detecting and managing memory leaks, garbage collection optimalizations.

Technology: Node.js, Redis, Docker,, Ansible, bash

Low-level MJPEG video stream parser and proxy application.

Technology: Node.js, Redis, Docker, bash


CRM system development for lead-management in real-estate. Microsites generator. Automated pricelist parser including unstructured format parsing from web crawler.

Technology: Python (Django framework), PostgreSQL, MySQL

Work experience

Software Development Engineer - Skype (3/2013 – 10/2013)

REST API development, work in environment of massively scaled (sharded) PostgreSQL databases.

Technology: PHP, Python, PostgreSql (PL/pgSQL, PgBouncer, PL/proxy)

Application developer - LMC s.r.o. (10/2011 – 2/2013)

Web applications development for biggest czech job portal

Technology: PHP, Javascript (AngularJS), XSLT, CouchDB, PostgreSQL, ActiveMQ, Fast ESP

PHP developer, software development manager - Internet retail a.s. (10/2005 – 9/2011)

Web applications development for a network of e-shops (,,, Backoffice apps, inventory management apps, automatic price management, automated communication with external suplliers.

Leading a team of developers.

Technology: PHP, MySQL