Calendar Heatmap
Native GitHub-contributions-style calendar heatmap. Give a year and `YYYY-MM-DD value` rows; days render as a 7×53 grid shaded by value with month and weekday labels and a legend. Ideal for activity, habits and daily time-series.
In the same space
Most users come to Calendar Heatmap from GitHub contribution graph or cal-heatmap. flowss runs this engine in the browser — no install, shareable via URL, exportable to PNG / SVG / PDF / source.
Syntax at a glance
year 2024
2024-03-20 11Paste this in the Studio code pane to see Calendar Heatmap render live. The full grammar is at the upstream-docs link above.
Sample templates
All 8 →Daily commit counts across a year.
Training days through the year.
Order volume by day with seasonal peaks.
Every page that woke the payments platform's primary on-call engineer in 2025: 569 pages over 252 days, with release days (Tuesday and Thursday) visibly darker, the ledger-migration incident week in mid-March peaking at 8 pages on Monday 17 March, the Black Friday surge and the quiet of the December change freeze. Illustrative values.
A year of 09:00–09:00 rain-gauge totals from an upland station: 1,078 mm across 200 wet days, wetter from October to February, and the October named storm standing out as the wettest day at 61.4 mm. Shading is relative to that storm day, so most ordinary wet days sit in the lighter bands. Illustrative values.
Daily randomisations into a fictional multicentre trial as sites open through the year: 398 participants in 2025, 119 in the first half and 279 in the second, with no randomisation at weekends, on the eight English bank holidays or over the Christmas closure. The thickening of the grid from spring onward is site activation, not seasonality. Illustrative values.
calendarheatmap · ← Browse all engines · Quick-start guide