Sunburst Chart: Visualizing Hierarchy in the Light of Radial Data

We continue our journey into the world of data visualization. Not long ago we broke down "Tree Map chart" in depth, and today it is time for the tool that many call the "king of hierarchies" — the Sunburst chart. This is not just a ring chart. It is a multi-level radial visualization where each inner circle is the parent of the outer one, and the size of each sector is strictly proportional to its value. If you need to show not only "how much" but also "what it consists of" — Sunburst handles it better than anyone else.

The data is the same real Requests (Cloudflare) and Edge Requests (Vercel) statistics from devitpro.uz. Behind the numbers are 64.87 thousand requests from 60 countries worldwide, 2.3 thousand unique visitors, and 51,785 requests through the Vercel Edge Network from 19 regions. The live traffic of a working project is the best training ground for honing visualization skills.

The Data Behind the Rays

We have two independent sources. The first is Requests (Cloudflare) for the period from September 1 to October 1, 2026. The second is Edge Requests (Vercel) for the period from June 28 to September 1, 2026. Below are the key figures.

How to Read a Sunburst Chart

Before we dive into our data, let us break down the anatomy. A Sunburst consists of concentric rings. The inner ring is the root level of the hierarchy (for example, "All requests"). The next ring is the first level of detail (for example, "Cloudflare" and "Vercel"). The outer rings are deeper levels (countries, regions, hosts).

The angle of each sector is proportional to its value. If the "United States" sector takes up 12.9% of the circle, it means the US accounts for 12.9% of all requests. When you hover over it, ECharts shows the exact value and the full path in the hierarchy. Clicking a sector lets you "drill down" into the node — this is called drilldown.

On this chart, you can see that the United States and Uzbekistan form the core of Cloudflare traffic — together they account for more than 21% of all requests. The Netherlands, Italy, and Germany form the second tier. Notice how the outer ring breaks into smaller sectors — these are the countries with a smaller share, yet they are still visible thanks to the radial structure.

Here the hierarchy is even more visible: the inner ring is the entire volume of Edge Requests, and the outer ring is the regions. Hong Kong (hkg1) occupies more than half of the circle. This is not an anomaly — it is strategic information: if you optimize infrastructure, look at hkg1 first.

What I Took Away From This Experience

• Sunburst is for hierarchies, not flat comparisons. If the data has no nested structure, a regular pie or bar chart will read better.
• Ring depth matters. Two or three levels is optimal. Five or more is already hard to read without drilldown.
• Color should reflect the hierarchy. Using the same shade for all children of one parent helps you see the structure instantly.
• Interactivity is mandatory. Without tooltips and drilldown, a Sunburst turns into a beautiful but useless picture.
• For SEO, text matters more than graphics. Search engine bots do not see canvas. That is why key figures and takeaways must live in the text — which we are doing.

Verdict: Is It Worth Learning Sunburst Charts in 2026?

The answer is a resounding yes. In a world where data is becoming more layered than ever (budgets, org structures, file systems, traffic geography), the ability to show hierarchy without losing context is a valuable skill. Sunburst is not a replacement for flat charts — it is a complement. It excels where you need to show nesting and proportions at the same time.

For me personally, this breakdown was another step in understanding how data structure drives the choice of visualization. And if you learn to see hierarchy where others see just a list, you will gain an advantage in any field of IT and AI.