Samuel Gratzl

Samuel Gratzl

Toolsmith for explorers of the information landscape on their treasure hunt for valuable insights

Samuel Gratzl is a passionate Research Software Engineer with a focus on interactive data exploration. He is a full-stack developer with 10+ years of experience. In 2017, he finished his PhD in Computer Science with a focus on Information Visualization at the Johannes Kepler University, Linz, Austria. He loves to dig into code, hunt bugs, and design new platforms. His goal is to enable researchers to discover more insights easier and faster, as well as develop libraries that help other developers do the same.


Information Visualization

D3, Vega,, ggplot2, matplotlib, Tableau, PowerBI

Data Science

Jupyter, RMarkdown, Quarto, Dash, RShiny, tidyverse, pandas, numpy


PostgresSQL, SQLServer, MongoDB, Redis, ElasticSearch, Neo4j, SQL

Frontend Developer

JavaScript/Typescript, React, Svelte, Vue

Backend Developer

R, Python, FastAPI, REST, Swagger, OpenAPI, GraphQL


GitHub, Git, Kubernetes, GitHub Action, Google Cloud, AWS


Principal Research Engineer
August 2021 – Present Remote
  • Being part of the research team analyzing healthcare data and providing feedback on current product developments.
  • Curated datasets based on the internal Truveta Platform.
  • Developed processes and templates for effective healthcare studies, speeding up our study creation
  • Created dashboards for Vaccine Effectiveness and Adverse Events of COVID-19 Vaccines
  • Identified data quality issues and supported clinical informatics in tracking them down.
  • Initiated and specified product features for advanced researcher experience.
Research Software Engineer Contractor
July 2020 – September 2021 Remote
  • Main front end developer of COVIDcast, a project by the Delphi Group collecting, publishing, and visualizing COVID-19 data..
  • Converted the front end from a research prototype to a production-ready product.
  • Enforced code quality and best practices throughout the project.
  • Improved usability, maintainability, and performance of COVIDcast.
  • Designed and implemented new views such as the National Survey Results View, the most popular COVIDcast view.
  • Designed and implemented a new version of the COVIDcast API with increased maintainability, scalability, and robustness.
  • Developed and deployed a new deployment infrastructure for the Delphi group.
Freelance Data Exploration and Visualization Consultant
Self Employed
October 2016 – March 2022 Linz, Austria
  • I specialize in the design and implementation of customized visual exploration web applications.
  • In close collaboration with the customer, I develop specialized visual exploration platforms that not only allow the customer to answer their questions but even those they haven’t thought about yet.}
  • In addition, I provide freelance service for integrating my open-source libraries, such as LinUp-lite, LineUp.js, or UpSet.js
Co-founder and Chief Technology Officer (CTO)
November 2016 – April 2019 Linz, Austria
  • Designed the architecture and implemented the Target Discovery Platform (TDP) with a focus on high extensibility and customizability. TDP is the foundation of all products of datavisyn and one of the three pillars of its business model.
  • Built and deployed overall CI/CD infrastructure both in-house and on-premise focusing on high-availability, fault tolerance, and low maintenance.
  • Lead on-site customer workshops focusing on requirements engineering, customer training, and initial prototype implementation.
  • Improved project requirements to the satisfaction of the customer.
  • Was the product owner for two agile customer projects which ended both in time and budget with highest customer satisfaction.
  • Implemented critical features in all (4+) customer projects of datavisyn.
  • Made customers happy through continuous customer support via Slack and quick response times.
  • Lead, trained, and mentored the three junior developers.
  • Did code reviews, introduced style guidelines, and introduced continuous testing to improve overall code quality.
  • Ensured the head start of the company over competitors through integrating new technologies and frameworks.


Promotio sub auspiciis Praesidentis rei publicae
I graduated my PhD with the highest possible honors in Austria with the presence of the president of Austria
Best Paper Award
For my paper titled “Provenance-Based Visualization Retrieval”
Honorable Mention Best Paper Award
For my paper titled “Pathfinder: Visual Analysis of Paths in Graphs”
Honorable Mention Best Paper Award
For my paper titled “Domino: Extracting, Comparing, and Manipulating Subsets across Multiple Tabular Datasets”
Best Paper Award
For my paper titled “LineUp: Visual Analysis of Multi-Attribute Rankings”


Cytoscape.js Plugins
Cytoscape.js is a population graph visualization library. I created several plugins for it
LineUp-lite is a React based simplified reimplementation of LineUp.js
UpSet.js is a JavaScript re-implementation of UpSetR which is an implementation of the UpSet visualization technique
YaCoBo - Yet another COVID-19 board
YaCoBo is dashboard application for COVID-19 COVIDcast data
MiniZinc Constraint Program Solver
Web IDE for the constraint programming language and solver MiniZinc
Chart.js Plugins
Chart.js is a popular Canvas based JavaScript visualization library. I created several plugins for it
Slack Cleaner 2
Modularized Version of the abandoned slack_cleaner utility
Target Discovery Platform (TDP)
Client Server platform for drug target discovery
LineUp: Visual Analysis of Multi-Attribute
LineUp is a visualization technique for multi-attribute rankings

Recent Publications

Quickly discover relevant content by filtering publications.
(2021). Uplift: A Tangible and Immersive Tabletop System for Casual Collaborative Visual Analytics. In IEEE Transactions on Visualization and Computer Graphics.


(2020). MaterialNet: A web-based graph explorer for materials science data. JOSS.

PDF Cite Code Project DOI Demo Application

(2020). Supporting the Problem-Solving Loop: Designing Highly Interactive Optimisation Systems. In IEEE Transactions on Visualization and Computer Graphics.

PDF Cite Project Video DOI

(2020). Viime: Visualization and Integration of Metabolomics Experiments. JOSS.

PDF Cite Code Project DOI

(2020). VisArch: visualisation of performance-based architectural refactorings. In Software Architecture.

Cite Project DOI