Jakub Gieryluk web & Android developer

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nationality / residence
Polish (EU national); residing in France
jakub.g.opensource or jakub.gieryluk
@jakub-g since 2012
active member since 2011
English (fluent)
Polish (native)
French (intermediate)
see my presentations
see my profile
profile for jakub.g at Stack Overflow profile for jakub.g at Stack Overflow


A seasoned front-end developer (web and mobile web), working full-time on Single Page Applications (SPAs) since 2012 (and part time since early 2000s - including backend work too); since 2017 also working with native Android.

Strong communication and analytical skills help him with transforming vague requirements into quality specs, writing solid code, doing thorough code reviews, debugging, finding edge cases and predicting the impossible, and doing post-mortem analyses.

A strong proponent of clean design and cutting complexity whenever possible.

With 5+ years of solid Git experience, Jakub is a go-to Git guy. He loves the power of the command line, and the composability of small scripts and modules.

If you've worked long enough with JavaScript, npm and git, there's a good chance you came across one of his answers on StackOverflow.

Professional experience, full-time (click to expand)

Android native developer, Amadeus IT Group, Sophia Antipolis, France 04.2017 - current

Part of a 2-dev Android native team. Implemented l10n/i18n code, processes & tooling; seamless user migration from the hybrid Cordova app; calendar and share-related code; and parts of the UI of the app.

  • Android
  • Java
  • Android Studio
  • Material Design
  • RxJava
  • Dagger
  • JUnit
  • Robolectric
  • Git

Senior front-end developer (Android & web), Amadeus IT Group, Sophia Antipolis, France 08.2015 - 04.2017

Worked in a 3-dev team on a 3-in-1 Android/mobile-web/desktop-web travel app (~2M Monthly Active Users) using Ionic Framework and Angular.js. The redesigned app's avg. monthly rating jumped to 4.5 in the Play Store.
Writing robust front-end code, automated tests (~70% coverage), specs; code reviews; tooling; cooperating with Product Owner and backend team on refining the functionalities and APIs; rotating in a scrum master role; involved in security discussions.
Implemented authentication & seamless account activation / forgot password flows; deep linking and push notifications functionalities; date/time & i18n handling code; integration with Google Places API; and parts of the UI of the app.
Set up a robust, automated build infrastructure on top of Jenkins, including a HipChat bot.
Carried out a tricky migration of the web app in a smooth and backward-compatible way.
Helped resolving & avoiding some critical HTTPS-related problems.

  • JavaScript
  • Angular.js
  • HTML5
  • CSS3
  • Ionic
  • Cordova
  • Android
  • Karma
  • Git
  • Jenkins
  • Chrome Dev Tools
  • NodeJS
  • Apache
  • Gulp
  • bower
  • npm
  • bash
  • Fiddler

Front-end developer (Android & web), Amadeus IT Group, Sophia Antipolis, France 01.2015 - 08.2015

Feature development, bugfixing, performance optimizations in a legacy codebase. Code reviews.

  • JavaScript
  • HTML5
  • CSS3
  • Cordova
  • Git
  • JSHint
  • Atlassian Stash
  • Chrome Dev Tools
  • bash
  • NodeJS
  • GruntJS
  • Fiddler

JavaScript UI frameworks developer, Amadeus IT Group, Sophia Antipolis, France 01.2012 - 01.2015

Core developer of an open-source UI & templating framework, used by 100+ developers, and related tools.
Implementing features in a big codebase in a backward-compatible way, fixing bugs. Improving testing tools, CI / build automation, tooling. Release management. Writing docs and blog articles, support.
Technical expert role in a team of ~15 developers: participating in technical discussions; establishing best practices; code reviews and code integration. Presenter during knowledge sharing sessions.
Extensive experience in debugging complex single-page web applications, cross-browser compatibility and front-end unit testing (Test-Driven Development). Working in agile methodology.

  • JavaScript
  • HTML5
  • CSS3
  • Git
  • GitHub
  • TravisCI
  • JSHint
  • Firebug
  • Chrome Dev Tools
  • IE Dev Tools
  • PhantomJS
  • bash
  • NodeJS
  • npm
  • GruntJS
  • Fiddler

Professional experience, part-time (click to expand)

Java web developer, QBICO s.c., Wroclaw, Poland 2010 - 2011

Employee #1 (after the co-owners) in a databases/business intelligence startup.
Programming data warehouse middleware and a full-text search engine, bugfixing, writing unit tests and builds.

  • Java
  • JSP
  • SQL
  • JUnit
  • Struts
  • Ant
  • Lucene
  • Eclipse

Full-stack web developer, Dictionary.com, remote 2010 - 2011

Worked on a multi-domain Single Sign-On & user profile area; email newsletter (backend, frontend, integration with SendGrid). Designed and implemented a mobile REST API. Bugfixes.

  • PHP
  • MySQL
  • CodeIgniter
  • Doctrine ORM
  • HTML
  • CSS

Web developer (summer intern), Volvo IT, Wroclaw, Poland 2009

Worked in a 5-dev team (agile) on an IT system for the HR department.

  • C#
  • HTML
  • CSS

Web developer, TopSolutions, Wroclaw, Poland 2009

Implementation of customer websites and internal tools. Search-engine optimization.

  • PHP
  • Zend Framework
  • MySQL
  • HTML
  • CSS
  • SEO

Web developer (freelance), remote 2002-2008

Creating and maintaining websites for various customers, in particular a website of a local basketball team.

  • PHP
  • HTML
  • CSS
  • JavaScript
  • MySQL
  • SEO

Education (click to expand)

Computer Science (M.Sc.Eng.), Wroclaw University of Technology (PWr), Poland 2006 - 2011

Graduated in June 2011, final grade: very good (avg. grade: 4.72 of max. 5.50).

Computer Science, Universidad Polit├ęcnica de Valencia (UPV), Spain 2009 - 2010

One-year scholarship. Avg. grade: 7.97 of max. 10.00.

Maths & Physics (profile), Boleslaw Chrobry High School, Brzeg, Poland 2003 - 2006

Polish Prime Minister Scholarship for school achievements (2004).
Maturity exam (state exam) results: Maths (98% basic, 100% extended), Physics (98% basic, 68% extended), English (97% basic written, 87% extended written, 100% oral).

Open-source contributions

Own projects (selection)

Major contributions

Minor contributions (selection)

Skills matrix

Web APIs
Single Page Applications
Cross-browser compat
Node.js & npm
Web performance & optimization
Web security
Java & its ecosystem
Build automation
Unit testing
Data modelling & API design
Backward compatibility
Release management
Command line tools
Technical estimations
Technical specifications
I18n & L10n
Time & date handling
User Experience
Design patterns