Online Tool Store
Heatmap Maker
Upload a CSV grid of numbers and generate a color-coded heatmap image. Runs entirely in your browser.
🔒 This tool runs entirely in your browser. Your files are never uploaded to a server.
Heatmap preview
Example shown — upload your own data to generate a matching heatmap.
How it works
- Upload a CSV grid of numeric values.
- Each cell is colored based on its value relative to the data range.
- Download the rendered heatmap as an image.
Rendering maps each cell's value onto a color scale — low values lighter, high values more saturated — the same visual encoding used by spreadsheet conditional formatting, without the manual setup.
FAQ
Is my data uploaded anywhere?
No. The heatmap is rendered entirely in your browser — your CSV is never sent to a server.
What data format does it expect?
A CSV grid of numeric values — each row and column becomes a cell in the heatmap, colored by its value.
Can I change the color scale?
Yes — choose from a few preset color scales to match your data's tone, from a single-hue intensity map to a diverging scale.
Can I download the result as an image?
Yes — download the rendered heatmap as a PNG for use in reports or presentations.
How we compare
| Feature | Online Tool Store | Spreadsheet conditional formatting | Python/plotting libraries |
|---|---|---|---|
| No manual setup per column | ✓ | Applied column by column | ✓ |
| Free, no setup | ✓ | ✓ | Requires a coding environment |
Python plotting libraries offer more control but need a coding environment. Heatmap Maker gives a clean visual result from a plain CSV upload.