diff --git a/experimental/kryo-hook/build.gradle b/experimental/kryo-hook/build.gradle
new file mode 100644
index 0000000000..cf52f3c9bb
--- /dev/null
+++ b/experimental/kryo-hook/build.gradle
@@ -0,0 +1,53 @@
+buildscript {
+    // For sharing constants between builds
+    Properties constants = new Properties()
+    file("$projectDir/../../constants.properties").withInputStream { constants.load(it) }
+
+    ext.kotlin_version = constants.getProperty("kotlinVersion")
+    ext.javaassist_version = "3.12.1.GA"
+
+    repositories {
+        mavenLocal()
+        mavenCentral()
+        jcenter()
+    }
+
+    dependencies {
+        classpath "org.jetbrains.kotlin:kotlin-gradle-plugin:$kotlin_version"
+    }
+}
+
+repositories {
+    mavenLocal()
+    mavenCentral()
+    jcenter()
+}
+
+apply plugin: 'kotlin'
+apply plugin: 'kotlin-kapt'
+apply plugin: 'idea'
+
+description 'A javaagent to allow hooking into Kryo'
+
+dependencies {
+    compile "org.jetbrains.kotlin:kotlin-stdlib-jre8:$kotlin_version"
+    compile "org.jetbrains.kotlin:kotlin-reflect:$kotlin_version"
+    compile "javassist:javassist:$javaassist_version"
+    compile "com.esotericsoftware:kryo:4.0.0"
+    compile "co.paralleluniverse:quasar-core:$quasar_version:jdk8"
+}
+
+jar {
+    archiveName = "${project.name}.jar"
+    manifest {
+        attributes(
+                'Premain-Class': 'net.corda.kryohook.KryoHookAgent',
+                'Can-Redefine-Classes': 'true',
+                'Can-Retransform-Classes': 'true',
+                'Can-Set-Native-Method-Prefix': 'true',
+                'Implementation-Title': "KryoHook",
+                'Implementation-Version': rootProject.version
+        )
+    }
+    from { configurations.compile.collect { it.isDirectory() ? it : zipTree(it) } }
+}
diff --git a/experimental/kryo-hook/src/main/kotlin/net/corda/kryohook/KryoHook.kt b/experimental/kryo-hook/src/main/kotlin/net/corda/kryohook/KryoHook.kt
new file mode 100644
index 0000000000..8d57dc8dbc
--- /dev/null
+++ b/experimental/kryo-hook/src/main/kotlin/net/corda/kryohook/KryoHook.kt
@@ -0,0 +1,159 @@
+package net.corda.kryohook
+
+import co.paralleluniverse.strands.Strand
+import com.esotericsoftware.kryo.Kryo
+import com.esotericsoftware.kryo.io.Output
+import javassist.ClassPool
+import javassist.CtClass
+import java.io.ByteArrayInputStream
+import java.lang.StringBuilder
+import java.lang.instrument.ClassFileTransformer
+import java.lang.instrument.Instrumentation
+import java.security.ProtectionDomain
+import java.util.concurrent.ConcurrentHashMap
+import java.util.concurrent.atomic.AtomicInteger
+
+class KryoHookAgent {
+    companion object {
+        @JvmStatic
+        fun premain(argumentsString: String?, instrumentation: Instrumentation) {
+            Runtime.getRuntime().addShutdownHook(Thread {
+                val statsTrees = KryoHook.events.values.flatMap {
+                    readTrees(it, 0).second
+                }
+                val builder = StringBuilder()
+                statsTrees.forEach {
+                    prettyStatsTree(0, it, builder)
+                }
+                print(builder.toString())
+            })
+            instrumentation.addTransformer(KryoHook)
+        }
+    }
+}
+
+fun prettyStatsTree(indent: Int, statsTree: StatsTree, builder: StringBuilder) {
+    when (statsTree) {
+        is StatsTree.Object -> {
+            builder.append(kotlin.CharArray(indent) { ' ' })
+            builder.append(statsTree.className)
+            builder.append(" ")
+            builder.append(statsTree.size)
+            builder.append("\n")
+            for (child in statsTree.children) {
+                prettyStatsTree(indent + 2, child, builder)
+            }
+        }
+    }
+}
+
+object KryoHook : ClassFileTransformer {
+    val classPool = ClassPool.getDefault()
+
+    val hookClassName = javaClass.name
+
+    override fun transform(
+            loader: ClassLoader?,
+            className: String,
+            classBeingRedefined: Class<*>?,
+            protectionDomain: ProtectionDomain?,
+            classfileBuffer: ByteArray
+    ): ByteArray? {
+        if (className.startsWith("java") || className.startsWith("javassist") || className.startsWith("kotlin")) {
+            return null
+        }
+        return try {
+            val clazz = classPool.makeClass(ByteArrayInputStream(classfileBuffer))
+            instrumentClass(clazz)?.toBytecode()
+        } catch (throwable: Throwable) {
+            println("SOMETHING WENT WRONG")
+            throwable.printStackTrace(System.out)
+            null
+        }
+    }
+
+    private fun instrumentClass(clazz: CtClass): CtClass? {
+        for (method in clazz.declaredBehaviors) {
+            if (method.name == "write") {
+                val parameterTypeNames = method.parameterTypes.map { it.name }
+                if (parameterTypeNames == listOf("com.esotericsoftware.kryo.Kryo", "com.esotericsoftware.kryo.io.Output", "java.lang.Object")) {
+                    if (method.isEmpty) continue
+                    println("Instrumenting ${clazz.name}")
+                    method.insertBefore("$hookClassName.${this::writeEnter.name}($1, $2, $3);")
+                    method.insertAfter("$hookClassName.${this::writeExit.name}($1, $2, $3);")
+                    return clazz
+                }
+            }
+        }
+        return null
+    }
+
+    val events = ConcurrentHashMap<Long, ArrayList<StatsEvent>>()
+    val eventCount = AtomicInteger(0)
+
+    @JvmStatic
+    fun writeEnter(kryo: Kryo, output: Output, obj: Any) {
+        events.getOrPut(Strand.currentStrand().id) { ArrayList() }.add(
+                StatsEvent.Enter(obj.javaClass.name, output.total())
+        )
+        if (eventCount.incrementAndGet() % 100 == 0) {
+            println("EVENT COUNT ${eventCount}")
+        }
+    }
+    @JvmStatic
+    fun writeExit(kryo: Kryo, output: Output, obj: Any) {
+        events.get(Strand.currentStrand().id)!!.add(
+                StatsEvent.Exit(obj.javaClass.name, output.total())
+        )
+    }
+}
+
+sealed class StatsEvent {
+    data class Enter(val className: String, val offset: Long) : StatsEvent()
+    data class Exit(val className: String, val offset: Long) : StatsEvent()
+}
+
+sealed class StatsTree {
+    data class Object(
+            val className: String,
+            val size: Long,
+            val children: List<StatsTree>
+    ) : StatsTree()
+}
+
+
+fun readTree(events: List<StatsEvent>, index: Int): Pair<Int, StatsTree> {
+    val event = events[index]
+    when (event) {
+        is StatsEvent.Enter -> {
+            val (nextIndex, children) = readTrees(events, index + 1)
+            val exit = events[nextIndex] as StatsEvent.Exit
+            require(event.className == exit.className)
+            return Pair(nextIndex + 1, StatsTree.Object(event.className, exit.offset - event.offset, children))
+        }
+        is StatsEvent.Exit -> {
+            throw IllegalStateException("Wasn't expecting Exit")
+        }
+    }
+}
+
+fun readTrees(events: List<StatsEvent>, index: Int): Pair<Int, List<StatsTree>> {
+    val trees = ArrayList<StatsTree>()
+    var i = index
+    while (true) {
+        val event = events.getOrNull(i)
+        when (event) {
+            is StatsEvent.Enter -> {
+                val (nextIndex, tree) = readTree(events, i)
+                trees.add(tree)
+                i = nextIndex
+            }
+            is StatsEvent.Exit -> {
+                return Pair(i, trees)
+            }
+            null -> {
+                return Pair(i, trees)
+            }
+        }
+    }
+}