YAN

HOLTZ

`Hello`I'm a dataviz engineer.

I build the custom charts off-the-shelf tools can't, with D3.js. Former Datadog engineer, creator of data-to-viz, the and many other dataviz references, read by 300,000 people a month.

Start a project See my work

﹀

consulting

How I can help

I design and build bespoke, interactive data visualizations for the web: custom dashboards, data explorers and charts that off-the-shelf tools can't deliver. A modern stack (D3.js + React), tailored to your data and your users.

Got a dataset, a dashboard, or a Shiny app that deserves better? Tell me about it, I'd love to help make it shine.

Contact me

“Yan helped our team to build a variety of data visualization tools in our 3RnD platform. He made our codebase more robust, communicated very well and delivered tools that integrated easily into the platform.
Highly recommend Yan's work!”

Brad CalvinCEO and Co-founder, AsedaSciences

“Yan has taught me everything I know about data visualization! He taught my group how to display data in clever ways, and has been responsible for our recent interactive website related to psychiatric epidemiology.
He is a super-bright guy – I can highly recommend him!”

John McGrathSenior Researcher at the Queensland Brain Institute

free resources

You may already know my websites

I build free educational websites about data visualization. Together, they get about 300,000 page views a month.

Dataviz Inspiration

Hundreds of the best dataviz projects, to find ideas for your next chart.

Data to Viz

A classification of chart types based on your data format, with caveats to avoid.

Data to Art

A gallery of projects that turn data into stunning, more or less abstract visuals.

The Dataviz Decision Tree

Which chart fits your data? A poster classifying chart types by input data format.

about

My story

My first chart was a Christmas tree, drawn in R during a genetics class instead of doing the assignment. It didn't get me a good grade, but it got me hooked.

After my master's, I crossed the Atlantic on a sailing boat. Halfway, that same teacher emailed me a job offer. I became a bioinformatician studying the wheat genome, and my favourite part was always the end of the pipeline: the chart.

On nights and weekends, I built the R Graph Gallery. It grew enough to land me a job at the Queensland Brain Institute in Australia, where I created data-to-viz.com. That led to Datadog, where I spent five years as a software engineer and fell for D3.js.

In 2024, my side projects had grown enough for me to go independent. I now build custom dataviz for clients, teach, and write a weekly newsletter. And I've never had to apply for a job.

Contact

teaching

Online courses

I've built 4 online courses, now followed by more than 2,000 students. Each one is hands-on and interactive, and focuses on one tool so you can go deep. Pick the one that matches your stack.

D3 ❤️ React

Interactive data visualization for the web, with D3.js and React.

My flagship course: build truly custom charts, the reliable way in the AI era.

Visit the course

Matplotlib Journey

Python dataviz with Matplotlib.

An all-in-one, highly interactive course to become a Matplotlib dataviz expert.

Visit the course

ggplot2 uncharted

Dataviz with R and ggplot2.

Master ggplot2 through coding, design and AI workflows. With Cédric Scherer.

Visit the course

Productive R Workflow

Clean, reproducible R projects.

Work faster and cleaner in R: turn messy scripts into reproducible projects.

Visit the course

projects

Portfolio

Client work, educational projects, data explorations and dataviz essays. Here is a glimpse of what I've built over the last few years, so you can see the kind of work I do.