A heatmap is a data visualization technique that uses color intensity to represent data values. Darker/warmer colors indicate higher values, while lighter/cooler colors indicate lower values. Heatmaps are commonly used for correlation matrices, spatial data distribution, and user behavior analysis.

Does this tool upload my data to a server?

No. This tool runs entirely in your browser. All data is processed locally on your device and never uploaded to any server. Your data remains completely private.

What export formats are supported?

The tool supports exporting heatmaps as high-resolution PNG images. The exported image matches the preview quality. You can adjust cell size settings to control output resolution.

What color schemes are available?

The tool offers multiple color schemes including: Red-Green, Blue-White, Cool-Warm, Rainbow, Plasma, Viridis, and Greyscale. You can choose the scheme that best fits your visualization needs.

What is the maximum data size supported?

We recommend keeping rows and columns within 20×20 (400 data points) for optimal display. Larger matrices may result in small cells that reduce readability. You can adjust cell size to accommodate larger datasets.

Free Online Heatmap Generator

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Updated: 2026-07-11

📊 Data Input

Rows: Columns:

🎨 Color & Settings

Cell Size: Show Values:

📈 Preview

Low

High

📖 How to Use

A heatmap is a powerful data visualization tool that uses color intensity to represent data values. This tool lets you create fully customizable matrix heatmaps with zero server-side processing.

Steps

Step 1: Set rows and columns, click "Update Matrix" to build the data table
Step 2: Enter your data values or click "Random Data" for sample data
Step 3: Choose a color scheme and cell size, then click "Generate"
Step 4: Export the heatmap as a high-resolution PNG image

When to use Online Heatmap Generator

Reports & Presentations: Visualize data distributions in professional documents
Academic Research: Gene expression matrices, correlation matrix visualization
Data Analysis: Quickly identify patterns, clusters, and outliers in your data
Business Intelligence: Sales performance, customer behavior, and market analysis

❓ FAQ

What's the difference between a heatmap and a choropleth map?

A choropleth map shows data distribution across geographic regions. A heatmap uses a color matrix to display relationships and patterns in abstract data. This tool generates matrix heatmaps, not geographic heatmaps.

How sharp is the exported PNG?

The exported PNG matches the preview quality. You can adjust the "Cell Size" setting to control the final image resolution. We recommend using "Large" or "X-Large" cell sizes for high-resolution output.

Does the tool support negative values?

Yes. The tool automatically maps the full data range to the color scale. Negative values are shown in cool colors (blues), positive values in warm colors (reds), and zero in neutral tones. This is ideal for correlation matrices (-1 to 1).

Will large datasets affect performance?

We recommend keeping the matrix within 20×20 (400 data points) for smooth performance on all devices. Larger datasets may cause slow rendering or small cell sizes that reduce readability.

Can I customize row and column labels?

Yes. Row and column labels are editable directly in the table. Simply click on any label to edit it. Labels are also included in the exported PNG image.

🔥 Online Heatmap Generator