Milan Slezák, Developer in Prague, Czech Republic
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Milan Slezák

Verified Expert  in Engineering

Java, JEE, & Android Developer

Prague, Czech Republic
Toptal Member Since
December 7, 2015

Milan is a highly skilled Java, JEE, and Android developer with over fifteen years of professional software development experience. He is a dedicated individual who is looking forward to working with clients to realize their visions and find solutions for their problems.


Medcorder, Inc.
Gradle, Bitrise, Dagger 2, RxJava, Firebase, Android SDK
Česká Spořitelna (Erste Group)
Git, Gradle, REST APIs, Retrofit, Near-field Communication (NFC), Android, Java
Vaadin, Spring, Java, Android




Preferred Environment

Spring, IntelliJ IDEA, Android, Java, Git, Linux

The most amazing...

...private project I've designed and developed is Meteor, the most popular weather forecast app in the Czech Republic, with more than 1.5 million active users.

Work Experience

Lead Android Developer

2019 - PRESENT
Medcorder, Inc.
  • Designed and developed Medcorder service Android client from scratch.
  • Closely cooperated with Medcorder team and contributed to overal product design.
  • Quickly reacted to device related problems to maximize positive user experience.
Technologies: Gradle, Bitrise, Dagger 2, RxJava, Firebase, Android SDK

Senior Android Developer

2016 - PRESENT
Česká Spořitelna (Erste Group)
  • Provided technical design for an Android application created from scratch.
  • Developed new pilot banking and non-banking functionalities into the app.
  • Integrated a proprietary NFC payment solution using a host card emulation.
  • Developed a new PTP payments' solution based on ultrasound.
Technologies: Git, Gradle, REST APIs, Retrofit, Near-field Communication (NFC), Android, Java

Founder, UX Designer, and Developer

2010 - PRESENT
  • Designed and developed Meteor, the most popular mobile meteorological application in the Czech Republic, with over 1.5 million active users.
  • Designed and developed Klara, yet another mobile weather forecasting application with over 0.5 million active users.
  • Developed a high-performance internal geocoder solution based on public OSM data and used it in the apps mentioned above.
  • Developed an internal map server and Android SDK based on open source technologies, also used in the apps mentioned above.
  • Contributed to parcel tracking an Android app and its back end.
Technologies: Vaadin, Spring, Java, Android

Senior Android Developer

2016 - 2018
  • Designed the technical aspects of an Android application.
  • Developed an analytical app module based on Mapbox SDK.
  • Developed a route optimization app module based on Google APIs.
Technologies: Git, Gradle, RxJava, Mapbox, Android, Java

System Architect

2008 - 2014
Maurice Ward & Co.
  • Analyzed, designed, and developed a highly modular internal ERP system.
  • Led and mentored a small-sized internal development team.
  • Integrated internal ERP with customers' informational systems (SAP mostly).
Technologies: Ant Design, Subversion (SVN), JavaScript, CSS, HTML, PostgreSQL, OSGi, Vaadin, Hibernate, Spring, Java

Software Engineer

2006 - 2008
  • Designed and developed a Cramer OSS migration solution for a mobile network operator.
  • Processed a variety of data sources and dealt with Cramer 6 API.
  • Analyzed, designed, and developed statistical software for the Office of the Government Representation in Property Affairs.
Technologies: Subversion (SVN), APIs, Pentaho Mondrian OLAP Engine, PL/SQL, SQL, Oracle, Java

J2EE Developer

2005 - 2006
  • Contributed to the development of a web-based community portal for a French mobile operator.
  • Fixed bugs and implemented new features according to specifications.
  • Solved performance issues to maximize the web app's throughput.
Technologies: Ant Design, Perforce, Servlet, Jakarta Server Pages (JSP), Resin, MySQL, Java


2002 - 2005
  • Developed information systems for health service organizations based on an internal rapid application development framework.
  • Designed and developed a JSR-168 to FastCGI bridge (also part of the diploma thesis).
  • Fixed bugs and performance issues. Designed reusable components for internal RAD.
Technologies: CSS, Sybase, SQL, HTML, Perl

Bored by tons of weather apps with the same look and feel? Klara is a bright, innovative, and easy to understand weather forecasting app I created. It's fast with a minimal footprint. Klara has 500K active users.

An Android client to the Medcorder service. The app was designed to record and transcribe speech with your doctor so that you can share and consult the recording in inter circles. It is secure and has lots of useful features like chatting and media sharing, live transcript highlighting, and appointments' planning. Also contains a unique database of almost all US health care provides.

The most popular rain forecast app in the Czech Republic. Easy, simple to use with a minimal footprint. It is based on a custom map solution so that more than 1.5 million users can enjoy the app for free without any attribution and ads.


Poketka used to be the NFC payment and loyalty program app for the biggest bank in Czechia, Ceska Sporitelna a. s. (Erste Group). Now, it is a testing lab of new features and technologies related to payments and daily banking.

An Android front end to the Drillinginfo business intelligence solution. A high-quality app that is designed to be used by customers with a Drillinginfo subscription. They can always be up to date regarding what's new on the oil and gas field.


Architecture and development of a warehouse management system made from scratch.

The most popular and detailed 3-day forecast in the Czech Republic.


Contributed to UI development of a desktop smartphone and customized the Android OS source code.

Dis 13

System for reporting of pharmaceuticals distribution according to:

Cramer Data Migration

Design and development of a data migration solution for a mobile network operator. The project involved data-source processing, consolidation, connection, and creation of the overall network model.
2000 - 2006

Master's Degree in Computer Science

University of Hradec Králové - Hradec Králové, Czech Republic


RxJava, Retrofit, REST APIs, Retrofit 2, Google API


Subversion (SVN), Eclipse IDE, IDEA IDE, Apache Ant, Git, Apache Maven, Gradle, Pentaho Mondrian OLAP Engine, Servlet, IntelliJ IDEA, Perforce, Canvas 2D


Hibernate, Spring, OSGi, Vaadin, Jakarta Server Pages (JSP), Android SDK, Dagger 2, Ant Design


Android, Linux, Firebase, Bitrise, Mapbox, Oracle


Java, XML, SQL, Kotlin, Perl, HTML, CSS, JavaScript


Object-oriented Programming (OOP), Mobile Development, REST


Database Modeling, PostgreSQL, PL/SQL, Sybase, Oracle PL/SQL, MySQL


Architecture, Resin, Near-field Communication (NFC), APIs, OpenStreetMap, App UX, Audio, Widgets, Java Secure Socket Extension (JSSE), OkHttp, Maps, User Interface (UI)

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