Table heatmap
Apply spreadsheet-style color-scale conditional formatting to a CSV/table and get a styled HTML table. Runs entirely in your browser, no upload.
About this tool
Table heatmap applies spreadsheet-style color-scale conditional formatting
to a CSV/table and gives you a styled HTML <table> with shaded numeric cells —
the kind of "heat map" you'd build in Excel or Google Sheets, ready to paste into a
report, email, or web page.
- Every cell that parses as a number is shaded by its value on the chosen color
scale. Numbers with thousands commas, a
$/€/£sign, a trailing%, or accounting-style(parentheses)negatives are all recognized. - Text cells and the header row are left plain so labels stay readable.
- Pick a color scale: red→yellow→green (default), green→yellow→red, the diverging blue→white→red, or a simple white→green / white→blue.
- Scale each column independently (default) so every column gets its own min→max range, or turn it off to color the whole table on one global scale.
- Pin the minimum, maximum, and (for diverging scales) the midpoint to fixed values — like Excel's number-type color-scale anchors — instead of the data range.
- Cell text color (black or white) is chosen automatically for contrast.
Privacy
Everything runs in your browser via WebAssembly — your data is never uploaded. Also available from the gizza CLI and in chat.
Common uses
- Turn a metrics or sales spreadsheet into a color-coded HTML table for a dashboard or report.
- Highlight highs and lows in a comparison table at a glance.
FAQ
Which cell values are recognized as numbers?
Anything that parses numerically after stripping formatting: thousands commas
(1,234.5), a leading $, €, or £, a trailing %, and accounting-style
(500) negatives. Cells that don't parse — labels, dates, blanks — are left
unshaded, as is the header row when header is on (the default).
Should I scale per column or across the whole table?
Per-column (the default) gives each column its own min→max range, so a "revenue in millions" column and a "percent growth" column both use the full color range — that's what Excel does per selection. Turn it off for one global scale when all columns share a unit. Note that pinning both min and max overrides per-column scaling entirely.
What does the midpoint setting do?
It only applies to the diverging scales (red→yellow→green, green→yellow→red, blue→white→red): the value you pin is mapped to the neutral middle color, with values below and above fanning out toward the two ends. Left unset, the midpoint sits halfway between min and max. Sequential scales (white→green, white→blue) ignore it.
Will numbers stay readable on dark cell colors?
Yes — each shaded cell's text is switched between near-black and white automatically based on the background's luminance (a WCAG-style contrast check), so values at the saturated ends of a scale remain legible.
Developer & Automation Access
Run it from the terminal
Same engine as this page, headless — via the gizza CLI:
gizza tool table-heatmap "region,q1,q2
North,120,90
South,60,150"New to the CLI? Get gizza →
Open it by URL
Pre-fill and auto-run this tool with query parameters — the names match the API/CLI:
https://gizza.ai/tools/table-heatmap/?data=region%2Cq1%2Cq2%0ANorth%2C120%2C90%0ASouth%2C60%2C150&scale=red-yellow-green&header=true&per_column=true&delimiter=%2CMachine-readable descriptor: tool.json — title + parameters JSON Schema for agents.