diff --git a/.gitignore b/.gitignore
index 27ae6f1..7e0589d 100644
--- a/.gitignore
+++ b/.gitignore
@@ -373,3 +373,4 @@ FodyWeavers.xsd
 # Local History for Visual Studio Code
 .history/
 
+heatmap
diff --git a/go.mod b/go.mod
new file mode 100644
index 0000000..684e6fd
--- /dev/null
+++ b/go.mod
@@ -0,0 +1,3 @@
+module heatmap
+
+go 1.17
diff --git a/heatmap.go b/heatmap.go
new file mode 100644
index 0000000..2447181
--- /dev/null
+++ b/heatmap.go
@@ -0,0 +1,93 @@
+package main
+
+import (
+	"bufio"
+	"encoding/csv"
+	"fmt"
+	"io"
+	"io/ioutil"
+	"log"
+	"os"
+	"strconv"
+	"time"
+)
+
+type ActivityLine struct {
+	Date             time.Time
+	CaloriesEstimate uint64
+}
+
+func main() {
+	csvFile, _ := os.Open("heat.csv")
+	reader := csv.NewReader(bufio.NewReader(csvFile))
+	var length int = 17
+	var days = make(map[time.Time]uint64)
+	for {
+		line, error := reader.Read()
+		if error == io.EOF {
+			break
+		} else if error != nil {
+			log.Fatal(error)
+		}
+		thisTime, error := time.Parse("2006-01-02", line[0])
+		thisTime = time.Date(thisTime.Year(), thisTime.Month(), thisTime.Day(), 0, 0, 0, 0, time.Local)
+		if error != nil {
+			fmt.Println(error)
+			break
+		}
+		cals, error := strconv.ParseUint(line[1], 10, 64)
+		if error != nil {
+			break
+		}
+
+		days[thisTime] = days[thisTime] + cals
+	}
+	start := time.Date(time.Now().Year()-1, time.Now().Month(), time.Now().Day(), 0, 0, 0, 0, time.Local)
+	svg := "<svg width=\"960\" height=\"152\"><g transform=\"translate(29.5,24)\"><g fill=\"none\" stroke=\"#ccc\">"
+	datePointer := start
+	var week int = 0
+	midnightThisMorning := time.Date(time.Now().Year(), time.Now().Month(), time.Now().Day(), 0, 0, 0, 0, time.Local)
+
+	var monthChange = false
+	var monthLabelSpots = make(map[string]int)
+	for {
+
+		var calsOnDay = days[datePointer]
+
+		if calsOnDay > 0 {
+			svg = fmt.Sprintf("%s\n<rect width=\"%v\" height=\"%v\" x=\"%v\" y=\"%v\" fill=\"#00FF00\"></rect>", svg, length, length, week*length, length*int(datePointer.Weekday()))
+		} else {
+			svg = fmt.Sprintf("%s\n<rect width=\"%v\" height=\"%v\" x=\"%v\" y=\"%v\" ></rect>", svg, length, length, week*length, length*int(datePointer.Weekday()))
+		}
+		datePointer = datePointer.Add(time.Hour * 24)
+
+		if datePointer.After(midnightThisMorning) {
+			break
+		}
+		if datePointer.Day() == 1 {
+			monthChange = true
+		}
+		if datePointer.Weekday() == time.Sunday {
+			week++
+			if monthChange {
+				monthLabelSpots[datePointer.Month().String()] = week * length
+				monthChange = false
+			}
+		}
+	}
+	svg = fmt.Sprintf("%s\n</g></g>", svg)
+
+	//week labels
+	//tODO: parameterize
+	svg = fmt.Sprintf("%s<g transform=\"translate(6, 16)\"><text x=\"0\" y=\"30\">Mon</text><text x=\"0\" y=\"64\">Wed</text><text x=\"0\" y=\"97\">Fri</text></g>", svg)
+
+	//month labels
+	svg = fmt.Sprintf("%s<g transform=\"translate(30,14)\">", svg)
+	for monthName := range monthLabelSpots {
+		svg = fmt.Sprintf("%s<text x=\"%v\" y=\"0\">%v</text>", svg, monthLabelSpots[monthName], monthName[:3])
+	}
+	svg = fmt.Sprintf("%s</g>", svg)
+
+	svg = fmt.Sprintf("%s</svg>", svg)
+	ioutil.WriteFile("heatmap.svg", []byte(svg), 0644)
+}