Jano Suchal, Developer in Bratislava, Bratislava Region, Slovakia
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Jano Suchal

Verified Expert  in Engineering

Software Developer

Bratislava, Bratislava Region, Slovakia
Toptal Member Since
March 24, 2014

Jano is a full-stack developer and founder specializing in databases. Using PostgreSQL, he has worked on database services with government data, recommendation engines, and performance optimization projects and has experience with startups, consulting, and leading small teams. Jano has a master's degree (summa cum laude) in software engineering from the Slovak University of Technology in Bratislava.


Amazon Web Services (AWS), Jira, PostgreSQL, Elasticsearch, Ruby on Rails (RoR)...
minio, s.r.o.
JavaScript, Redis, Elasticsearch, PostgreSQL, Ruby on Rails (RoR), Full-stack...
SearchD/Luigi's Box
SaltStack, PostgreSQL, Redis, Elasticsearch, Ruby on Rails (RoR), Full-stack




Preferred Environment

Linux, PostgreSQL, Ruby, Agile Software Development

The most amazing...

...things I've built are apps using public data in Slovakia, making contracts and public registers easier to use for journalists and the general public.

Work Experience

Lead Developer and Project Manager

2015 - PRESENT
  • Led a small team of developers and freelancers to build parallel, low-cost e-government services.
  • Created a platform for downloading/cleaning public open data sets with millions of entries and gigabytes of data.
  • Built a fast autocomplete search based on Elasticsearch.
  • Managed multiple servers serving staging/production environments with Docker-based deployment.
  • Supported various tools needed for business (Trello, Jira, email servers, billing, AWS).
Technologies: Amazon Web Services (AWS), Jira, PostgreSQL, Elasticsearch, Ruby on Rails (RoR), Redis, CTO, Full-stack


2011 - PRESENT
minio, s.r.o.
  • Created a platform for scraping various public government registers and databases.
  • Built a platform for automatic data disambiguation, cleaning, and reconciliation of multiple messy public datasets.
  • Managed traffic/performance analytics for several projects.
  • Built a platform for making government contracts transparently available for anyone in Slovakia.
  • Managed a search engine with 600,000+ documents (TBs of raw data).
  • Organized a monthly polyglot developer meet-up in Bratislava every month since 2011.
  • Created a system for fraud detection in European Social Fund project proposals.
Technologies: JavaScript, Redis, Elasticsearch, PostgreSQL, Ruby on Rails (RoR), Full-stack, Polyglot Persistence

Senior Developer

2013 - 2015
SearchD/Luigi's Box
  • Created a scalable log processing pipeline analyzing millions of events.
  • Designed advanced metrics and reports for testing and evaluation of real-world search engines.
  • Contributed to the full stack—from business goals through front-end tuning to back-end development and tuning.
  • Ensured high code quality by enforcing automatic testing on the build server, code coverage trend reporting, and code reviews.
  • Proposed and successfully implemented business process changes to optimize signup and onboarding funnels, yielding an increase in goal conversions.
Technologies: SaltStack, PostgreSQL, Redis, Elasticsearch, Ruby on Rails (RoR), Full-stack

Senior Back-end Developer

2011 - 2013
  • Created a recommendation engine for movies and television shows.
  • Built a logging and quality evaluation platform for a recommendation engine and search-related sub-projects.
  • Proposed and measured several UX enhancements on user-facing pages.
  • Created a crawling service scraping data from various online sources.
  • Implemented various duplicate matching algorithms for cleaning and disambiguating data.
Technologies: PostgreSQL, Redis, Elasticsearch, Ruby on Rails (RoR)


2010 - 2012
  • Created and sold a project to download, clean, and update data about over 300,000 companies and 500,000 people from the official registers of Slovak companies, public procurement, debts, internet domains, and other public data.
  • Supported a complex site handling over 500,000 page views a month.
  • Created a framework for scraping, cleaning, and merging messy datasets.
  • Built various visualizations and aggregation reports from gathered data.
  • Fine-tuned autocomplete search for highly relevant instant responses.
Technologies: Sphinx Search Engine, MySQL, Ruby on Rails (RoR), CTO, Full-stack

Researcher | PhD Student

2008 - 2011
Faculty of Informatics and Information Technologies
  • Built a news recommendation engine for the largest Slovak newspaper peaking at 3,000+ rpm.
  • Created and led a new course on full-stack web development.
  • Published multiple articles on recommendation systems and data mining.
  • Led multiple teams of students on various projects.
  • Built and supported various faculty websites and apps.
Technologies: SQL, R, Ruby on Rails (RoR), Ruby


2001 - 2011
  • Built a "did you mean?" search feature for a major music website in Slovakia.
  • Built and maintained web applications for various SMEs.
  • Consulted several clients regarding SQL performance fine-tuning.
  • Created a popular random text generator for designers.
  • Handled basic HTML/CSS work for various clients in the eCommerce sector.
Technologies: PostgreSQL, MySQL, JavaScript, Ruby on Rails (RoR), PHP


Movie and TV show recommendation system and social site.

Open Contracts

A crowdsourcing platform for searching and analyzing government contracts. It provides a much more usable interface to work with contracts of Slovak governmental organizations in comparison to the official government site. It downloads and processes over 300k scanned documents (over 1TB of raw data) in various formats from many sources and transforms them into an easily searchable format using full text and advanced faceted search. Contracts are automatically analyzed and assigned a score indicating how problematic the contract is. This analysis is based on the rules managed by portal administrators.

Social Network of Slovak Companies

This site downloads, cleans, and updates data about over 300k companies and 500k people from official registers of Slovak companies, public procurements, debts, internet domains, and other public data. It shows all current and historic data about companies in an aggregated and usable form. It visualizes connections of people and companies as network (graphs) for deeper insights. It is used heavily by the public and private sector and handles traffic of over 500k page views per month.

API for All Slovak Government Data

An API for retrieving cleaned, reconciled, and merged data scraped from various public datasets and registers.

SearchD/Luigis's Box

Search analytics platform collecting and evaluating millions of events in real time.

Fraud Detection in European Social Fund Project Proposals

This crawls a legacy internal project management system and collects data about projects. It features enrichment of this data from other external sources: Slovak company register, register of NGOs, and the statistical office of the Slovak Republic. It involves extensive data cleaning, reverse duplication routines, and heuristics to match and distinguish subjects.

It identifies conflicts of interests between various stakeholders of the project by analyzing relationships within data.


A Google Analytics gem for Rails application performance that works by passing request profiling and timing data into Google Analytics. Also, allows performance analysis in Google Analytics and finding bottlenecks.
2007 - 2011

PhD (Unfinished) Degree in Machine learning

Slovak University of Technology - Bratislava

2005 - 2007

Master's (Summa Cum Laude) Degree in Software Engineering

Slovak University of Technology - Bratislava

2001 - 2005

Bachelor's Degree in Informatics

Slovak University of Technology - Bratislava


Twitter API, Facebook API, jQuery, GitHub API, Sidekiq


RSpec, SaltStack, Jira, Git, GitHub, RubyMine


Ruby on Rails (RoR), Sinatra


Salesforce, Linux, Amazon Web Services (AWS), Docker


Ruby, SQL, PHP, JavaScript, R, CoffeeScript, HTML5


Agile Software Development, Test-driven Development (TDD), Object-oriented Design (OOD), Behavior-driven Development (BDD), Dependency Injection


Elasticsearch, Redis, PostgreSQL, MySQL, Sphinx Search Engine, Polyglot Persistence


API Integration, APIs, Machine Learning, Recommendation Systems, Full-stack, Consulting, CTO, Analytics

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