diff --git a/core/shared/src/main/scala/plotly/Sequence.scala b/core/shared/src/main/scala/plotly/Sequence.scala
old mode 100644
new mode 100755
index 50b6cec..db872d4
--- a/core/shared/src/main/scala/plotly/Sequence.scala
+++ b/core/shared/src/main/scala/plotly/Sequence.scala
@@ -7,6 +7,7 @@ sealed abstract class Sequence extends Product with Serializable
 object Sequence {
   final case class Doubles(seq: Seq[Double]) extends Sequence
   final case class NestedDoubles(seq: Seq[Seq[Double]]) extends Sequence
+  final case class NestedInts(seq: Seq[Seq[Int]]) extends Sequence
   final case class Strings(seq: Seq[String]) extends Sequence
   final case class DateTimes(seq: Seq[LocalDateTime]) extends Sequence
 
@@ -20,6 +21,8 @@ object Sequence {
     Doubles(s.map(_.toDouble))
   implicit def fromNestedDoubleSeq(s: Seq[Seq[Double]]): Sequence =
     NestedDoubles(s)
+  implicit def fromNestedIntSeq(s: Seq[Seq[Int]]): Sequence =
+    NestedInts(s)
   implicit def fromStringSeq(s: Seq[String]): Sequence =
     Strings(s)
   implicit def fromDateTimes(seq: Seq[LocalDateTime]): Sequence =
diff --git a/core/shared/src/main/scala/plotly/Trace.scala b/core/shared/src/main/scala/plotly/Trace.scala
old mode 100644
new mode 100755
index 9b990b0..db0d457
--- a/core/shared/src/main/scala/plotly/Trace.scala
+++ b/core/shared/src/main/scala/plotly/Trace.scala
@@ -260,3 +260,34 @@ object Surface {
       Option(opacity)   .map(d => d: Double)
     )
 }
+
+@data class Heatmap(
+             y: Option[Sequence],
+             x: Option[Sequence],
+             z: Option[Sequence],
+autocolorscale: Option[Boolean],
+    colorscale: Option[ColorScale],
+     showscale: Option[Boolean],
+          name: Option[String]
+) extends Trace
+
+object Heatmap {
+  def apply(
+               y: Sequence        = null,
+               x: Sequence        = null,
+               z: Sequence        = null,
+  autocolorscale: JBoolean        = null,
+      colorscale: ColorScale      = null,
+       showscale: JBoolean        = null,
+            name: String          = null
+  ): Heatmap =
+    Heatmap(
+      Option(y),
+      Option(x),
+      Option(z),
+      Option(autocolorscale).map(b => b: Boolean),
+      Option(colorscale),
+      Option(showscale).map(b => b: Boolean),
+      Option(name)
+    )
+}
diff --git a/core/shared/src/main/scala/plotly/element/ColorScale.scala b/core/shared/src/main/scala/plotly/element/ColorScale.scala
new file mode 100755
index 0000000..cefb566
--- /dev/null
+++ b/core/shared/src/main/scala/plotly/element/ColorScale.scala
@@ -0,0 +1,9 @@
+package plotly.element
+import dataclass.data
+
+sealed abstract class ColorScale extends Product with Serializable
+
+object ColorScale {
+  @data class CustomScale(values: Seq[(Double, Color)]) extends ColorScale
+  @data class NamedScale(name: String) extends ColorScale
+}
\ No newline at end of file
diff --git a/core/shared/src/main/scala/plotly/element/Ticks.scala b/core/shared/src/main/scala/plotly/element/Ticks.scala
old mode 100644
new mode 100755
index 9142bd7..90dc43d
--- a/core/shared/src/main/scala/plotly/element/Ticks.scala
+++ b/core/shared/src/main/scala/plotly/element/Ticks.scala
@@ -5,4 +5,6 @@ sealed abstract class Ticks(val label: String) extends Product with Serializable
 
 object Ticks {
   case object Outside extends Ticks("outside")
+  case object Inside extends Ticks("inside")
+  case object Empty extends Ticks("")
 }
diff --git a/core/shared/src/main/scala/plotly/layout/Axis.scala b/core/shared/src/main/scala/plotly/layout/Axis.scala
old mode 100644
new mode 100755
index 3aed94d..6dcb30e
--- a/core/shared/src/main/scala/plotly/layout/Axis.scala
+++ b/core/shared/src/main/scala/plotly/layout/Axis.scala
@@ -23,6 +23,8 @@ import plotly.element._
            dtick: Option[Double],
          ticklen: Option[Int],
         tickfont: Option[Font],
+      tickprefix: Option[String],
+      ticksuffix: Option[String],
         zeroline: Option[Boolean],
    zerolinewidth: Option[Double],
    zerolinecolor: Option[Color],
@@ -60,6 +62,8 @@ object Axis {
              dtick: JDouble          = null,
            ticklen: JInt             = null,
           tickfont: Font             = null,
+        tickprefix: String           = null,
+        ticksuffix: String           = null,
           zeroline: JBoolean         = null,
      zerolinewidth: JDouble          = null,
      zerolinecolor: Color            = null,
@@ -95,6 +99,8 @@ object Axis {
       Option(dtick)          .map(x => x: Double),
       Option(ticklen)        .map(x => x: Int),
       Option(tickfont),
+      Option(tickprefix),
+      Option(ticksuffix),
       Option(zeroline)       .map(x => x: Boolean),
       Option(zerolinewidth)  .map(x => x: Double),
       Option(zerolinecolor),
diff --git a/demo/src/main/scala/plotly/demo/Demo.scala b/demo/src/main/scala/plotly/demo/Demo.scala
old mode 100644
new mode 100755
index 20e2a97..df2d42f
--- a/demo/src/main/scala/plotly/demo/Demo.scala
+++ b/demo/src/main/scala/plotly/demo/Demo.scala
@@ -37,6 +37,12 @@ import scalatags.JsDom.all.{area => _, _}
     ),
     "Filled Area Plots" -> Seq(
       area.BasicOverlaidAreaChart
+    ),
+    "Heatmaps" -> Seq(
+      heatmaps.BasicHeatmap,
+      heatmaps.CategoricalAxisHeatmap,
+      heatmaps.CustomColorScaleHeatmap,
+      heatmaps.AnnotatedHeatmap
     )
   )
 
diff --git a/demo/src/main/scala/plotly/demo/heatmaps/AnnotatedHeatmap.scala b/demo/src/main/scala/plotly/demo/heatmaps/AnnotatedHeatmap.scala
new file mode 100755
index 0000000..400d4fc
--- /dev/null
+++ b/demo/src/main/scala/plotly/demo/heatmaps/AnnotatedHeatmap.scala
@@ -0,0 +1,55 @@
+package plotly.demo.heatmaps
+
+import plotly._
+import plotly.demo.DemoChart
+import plotly.element._
+import plotly.layout._
+
+object AnnotatedHeatmap extends DemoChart {
+
+  def plotlyDocUrl = "https://plot.ly/javascript/heatmaps/#annotated-heatmap"
+  def id = "annotated-heatmap"
+  def source = AnnotatedHeatmapSource.source
+
+  // demo source start
+
+  val x = Seq("A", "B", "C", "D", "E");
+  val y = Seq("W", "X", "Y", "Z");
+  val z = Seq(
+    Seq(0.00, 0.00, 0.75, 0.75, 0.00),
+    Seq(0.00, 0.00, 0.75, 0.75, 0.00),
+    Seq(0.75, 0.75, 0.75, 0.75, 0.75),
+    Seq(0.00, 0.00, 0.00, 0.75, 0.00)
+  )
+
+  val data = Seq(
+    Heatmap(
+      z=z, x=x, y=y, showscale=false,
+      colorscale = ColorScale.CustomScale(Seq(
+        (0, Color.StringColor("#3D9970")),
+        (1, Color.StringColor("#001f3f"))
+      ))
+    )
+  )
+
+  val layout = Layout(
+    title = "Annotated Heatmap",
+    xaxis = Axis(ticks=Ticks.Empty, side=Side.Top),
+    yaxis = Axis(ticks=Ticks.Empty, ticksuffix=" "),
+    annotations = for {
+      (xv, xi) <- x.zipWithIndex;
+      (yv, yi) <- y.zipWithIndex
+    } yield Annotation(
+      x=xv,
+      y=yv,
+      xref=Ref.Axis(AxisReference.X1),
+      yref=Ref.Axis(AxisReference.Y1),
+      showarrow=false,
+      text=z(yi)(xi).toString,
+      font=Font(color=Color.StringColor("white"))
+    )
+  )
+
+  // demo source end
+
+}
\ No newline at end of file
diff --git a/demo/src/main/scala/plotly/demo/heatmaps/BasicHeatmap.scala b/demo/src/main/scala/plotly/demo/heatmaps/BasicHeatmap.scala
new file mode 100755
index 0000000..281b27f
--- /dev/null
+++ b/demo/src/main/scala/plotly/demo/heatmaps/BasicHeatmap.scala
@@ -0,0 +1,28 @@
+package plotly.demo.heatmaps
+
+import plotly._
+import plotly.demo.NoLayoutDemoChart
+import plotly.element._
+
+object BasicHeatmap extends NoLayoutDemoChart {
+
+  def plotlyDocUrl = "https://plot.ly/javascript/heatmaps/#basic-heatmap"
+  def id = "basic-heatmap"
+  def source = BasicHeatmapSource.source
+
+  // demo source start
+
+  val data = Seq(
+    Heatmap(
+      z=Seq(
+        Seq(1, 20, 30),
+        Seq(20, 1, 60),
+        Seq(30, 60, 1)
+      ),
+      colorscale=ColorScale.NamedScale("Portland")
+    )
+  )
+
+  // demo source end
+
+}
\ No newline at end of file
diff --git a/demo/src/main/scala/plotly/demo/heatmaps/CategoricalAxisHeatmap.scala b/demo/src/main/scala/plotly/demo/heatmaps/CategoricalAxisHeatmap.scala
new file mode 100755
index 0000000..725a04f
--- /dev/null
+++ b/demo/src/main/scala/plotly/demo/heatmaps/CategoricalAxisHeatmap.scala
@@ -0,0 +1,29 @@
+package plotly.demo.heatmaps
+
+import plotly._
+import plotly.demo.NoLayoutDemoChart
+import plotly.element._
+
+object CategoricalAxisHeatmap extends NoLayoutDemoChart {
+
+  def plotlyDocUrl = "https://plot.ly/javascript/heatmaps/#heatmap-with-categorical-axis-labels"
+  def id = "categorical-axis-heatmap"
+  def source = CategoricalAxisHeatmapSource.source
+
+  // demo source start
+
+  val data = Seq(
+    Heatmap(
+      z=Seq(
+        Seq(1, null.asInstanceOf[Int], 30, 50, 1),
+        Seq(20, 1, 60, 80, 30),
+        Seq(30, 60, 1, -10, 20)
+      ),
+      x=Seq("Monday", "Tuesday", "Wednesday", "Thursday", "Friday"),
+      y=Seq("Morning", "Afternoon", "Evening"),
+    )
+  )
+
+  // demo source end
+
+}
\ No newline at end of file
diff --git a/demo/src/main/scala/plotly/demo/heatmaps/CustomColorScaleHeatmap.scala b/demo/src/main/scala/plotly/demo/heatmaps/CustomColorScaleHeatmap.scala
new file mode 100755
index 0000000..1e2a69d
--- /dev/null
+++ b/demo/src/main/scala/plotly/demo/heatmaps/CustomColorScaleHeatmap.scala
@@ -0,0 +1,37 @@
+package plotly.demo.heatmaps
+
+import plotly._
+import plotly.demo.NoLayoutDemoChart
+import plotly.element._
+
+object CustomColorScaleHeatmap extends NoLayoutDemoChart {
+
+  def plotlyDocUrl = "https://plot.ly/javascript/colorscales/#custom-colorscale-for-contour-plot"
+  def id = "custom-colorscale-heatmap"
+  def source = CustomColorScaleHeatmapSource.source
+
+  // demo source start
+
+  val data = Seq(
+    Heatmap(
+      z=Seq(
+        Seq(10.0, 10.625, 12.5, 15.625, 20.0),
+        Seq(5.625, 6.25, 8.125, 11.25, 15.625),
+        Seq(2.5, 3.125, 5.0, 8.125, 12.5),
+        Seq(0.625, 1.25, 3.125, 6.25, 10.625),
+        Seq(0.0, 0.625, 2.5, 5.625, 10.0)
+      ),
+      colorscale=ColorScale.CustomScale(Seq(
+        (0, Color.RGB(166,206,227)),
+        (0.25, Color.RGB(31,120,180)),
+        (0.45, Color.RGB(178,223,138)),
+        (0.65, Color.RGB(51,160,44)),
+        (0.85, Color.RGB(251,154,153)),
+        (1, Color.RGB(227,26,28))
+      ))
+    )
+  )
+
+  // demo source end
+
+}
\ No newline at end of file
diff --git a/plotly-documentation b/plotly-documentation
index ef7ce85..eae136b 160000
--- a/plotly-documentation
+++ b/plotly-documentation
@@ -1 +1 @@
-Subproject commit ef7ce858e251eb30d345b20e6684c5afc56de674
+Subproject commit eae136bb920c7542654a5e13cff04a0de175a08d
diff --git a/project/make-ghpages.sh b/project/make-ghpages.sh
index 7a2239d..276e5ba 100755
--- a/project/make-ghpages.sh
+++ b/project/make-ghpages.sh
@@ -6,17 +6,17 @@ if [ -e gh-pages ]; then
   exit 1
 fi
 
-sbt demo/fullOptJS
+./sbt demo/fullOptJS
 mkdir gh-pages
 
 cp \
-  demo/target/scala-2.11/plotly-demo-opt.js \
-  demo/target/scala-2.11/plotly-demo-opt.js.map \
-  demo/target/scala-2.11/plotly-demo-jsdeps.js \
-  demo/target/scala-2.11/plotly-demo-jsdeps.min.js \
+  demo/target/scala-2.13/plotly-demo-opt.js \
+  demo/target/scala-2.13/plotly-demo-opt.js.map \
+  demo/target/scala-2.13/plotly-demo-jsdeps.js \
+  demo/target/scala-2.13/plotly-demo-jsdeps.min.js \
   gh-pages
 
-cat demo/target/scala-2.11/classes/index.html | \
+cat demo/target/scala-2.13/classes/index.html | \
   sed 's@\.\./plotly-demo-jsdeps\.js@plotly-demo-jsdeps.min.js@' | \
   sed 's@\.\./plotly-demo-fastopt\.js@plotly-demo-opt.js@' | \
   cat > gh-pages/index.html
diff --git a/render/shared/src/main/scala/plotly/internals/ArgonautCodecsInternals.scala b/render/shared/src/main/scala/plotly/internals/ArgonautCodecsInternals.scala
old mode 100644
new mode 100755
index 59cc86d..0c5ded6
--- a/render/shared/src/main/scala/plotly/internals/ArgonautCodecsInternals.scala
+++ b/render/shared/src/main/scala/plotly/internals/ArgonautCodecsInternals.scala
@@ -46,6 +46,7 @@ object ArgonautCodecsInternals extends ArgonautCodecsExtra {
   implicit val boxPointsBoolIsWrapper: IsWrapper[BoxPoints.Bool] = null
   implicit val sequenceDoublesIsWrapper: IsWrapper[Sequence.Doubles] = null
   implicit val sequenceNestedDoublesIsWrapper: IsWrapper[Sequence.NestedDoubles] = null
+  implicit val sequenceNestedIntsIsWrapper: IsWrapper[Sequence.NestedInts] = null
   implicit val sequenceStringsIsWrapper: IsWrapper[Sequence.Strings] = null
   implicit val sequenceDatetimesIsWrapper: IsWrapper[Sequence.DateTimes] = null
   implicit val doubleElementIsWrapper: IsWrapper[Element.DoubleElement] = null
@@ -377,6 +378,30 @@ object ArgonautCodecsInternals extends ArgonautCodecsExtra {
       }
     }
 
+  implicit val encodeNamedColorScale: EncodeJson[ColorScale.NamedScale] =
+    EncodeJson.of[String].contramap(_.name)
+
+  implicit val decodeNamedColorScale: DecodeJson[ColorScale.NamedScale] =
+    DecodeJson { c =>
+      c.as[String].flatMap { s =>
+        // TODO: Add colorscale name enum?
+        DecodeResult.ok(ColorScale.NamedScale(s))
+      }
+    }
+
+  implicit val encodeCustomColorScale: EncodeJson[ColorScale.CustomScale] =
+    EncodeJson.of[Json].contramap(_.values.toList.asJson)
+
+  implicit val decodeCustomColorScale: DecodeJson[ColorScale.CustomScale] =
+    DecodeJson { c =>
+      c.as[Seq[(Double, Color)]].flatMap { s =>
+        DecodeResult.ok(ColorScale.CustomScale(s))
+      }
+    }
+
+  implicit val colorscaleJsonCodec: JsonSumCodecFor[ColorScale] =
+    JsonSumCodecFor(jsonSumDirectCodecFor("colorscale"))
+
   implicit val elementJsonCodec: JsonSumCodecFor[Element] =
     JsonSumCodecFor(jsonSumDirectCodecFor("element"))
 
diff --git a/tests/src/test/scala/plotly/doc/DocumentationTests.scala b/tests/src/test/scala/plotly/doc/DocumentationTests.scala
old mode 100644
new mode 100755
index b7dfaad..c409e80
--- a/tests/src/test/scala/plotly/doc/DocumentationTests.scala
+++ b/tests/src/test/scala/plotly/doc/DocumentationTests.scala
@@ -109,7 +109,7 @@ object DocumentationTests {
     // stub...
     def getElementById(id: String): String = id
   }
-  
+
   private object Numeric {
     def linspace(from: Int, to: Int, count: Int) = {
       val step = (to - from).toDouble / (count - 1)
@@ -243,6 +243,7 @@ class DocumentationTests extends FlatSpec with Matchers {
     "statistical/box",
     // TODO 2D Density plots
     "statistical/histogram",
+    "scientific/heatmap",
     // TODO 2D Histograms
     // TODO Wind rose charts
     // TODO Contour plots