Violin Plot Density Overlay Tool: Distributions with Density Curves, Free & Online

Use this free violin plot density overlay tool in your browser. No sign-up, no download and no upload: everything runs on your own device, so your data stays private.

What this tool does

Averages hide shape: two groups can share a mean while one is bimodal and the other is tight. A violin plot draws the full density shape for each group, mirrored around a centre line, with the median marked. This tool estimates density with a Gaussian kernel, so the width at any height shows how many values sit there.

How to use it

Paste or type your group value lists in the box above.
Adjust any settings, such as cutoffs, scales or styles, to match your data.
Click the run button and read the output below the tool.
Check the summary numbers before you copy anything into a document.
Copy the output, code or image into your figure, slide or report.

Worked example

Enter Control values around 12–16 and Treatment values around 19–24. The control violin is narrow and low, the treatment violin is narrow and high, and the red median lines sit far apart, which tells the treatment story better than two means alone. Add a few high outliers to Control and its violin stretches upward at once.

Tips for better results

Always show the sample size beside each violin, because shapes from tiny samples look deceptively smooth.

Honest limits

Density estimates need enough points to be meaningful; with fewer than about eight values per group, the shape is mostly guesswork. The tool does not test significance.

Choosing the right settings

Start with the default values. They are chosen to show a sensible result at once, so you can see the layout before you touch your own data. Then change one setting at a time. Changing one thing at a time is the fastest way to learn what each control does, and it stops two changes from cancelling each other out. If the output looks wrong, check the input format first: a missing comma, a swapped column or a stray space causes most errors, and the tool reports what it received in its summary line.

Using the result in a figure

For a figure, keep the output simple. One message per figure, short labels, and a caption that states the method and the settings you used will serve readers better than a dense, decorated chart. If a journal or supervisor will see the result, note the tool name, the input values and any cutoff in your methods or caption, so the figure can be reproduced later. That habit also helps you: six months from now, the caption is the only record of how the figure was made.

Common questions

Do I need an account? No. The violin plot density overlay tool runs entirely in your browser with no sign-up and no saved data.

Is my data uploaded anywhere? No. Your group value lists stays on your device, which is why the tool is safe for unpublished work.

Can I use the output in a paper or presentation? Yes. The output is yours to reuse; just check it visually once, note the settings in your caption, and credit the method, not the tool, in your references.

What if the result looks wrong? Check the input format first, then change one setting at a time. Most errors come from a missing comma, a swapped column, or a value outside the expected range, and the summary line under the tool shows what it actually received.

Try the violin plot density overlay tool above with the sample data, then with your own. It is free, it needs no account, and it works in any modern browser.

When you reuse the result, keep a short record of the inputs and settings you used. A one-line note in your project file, such as the data pasted, the cutoff chosen and the date, is enough to reproduce the figure later. If a collaborator questions a number, that note lets you rebuild the exact output in seconds instead of guessing what changed.

Embed this tool on your website — free

Copy the code below to add this working tool to your own page. A small credit link stays with it — that’s all we ask.