diff --git a/tfjs-backend-wasm/rollup.config.js b/tfjs-backend-wasm/rollup.config.js
index 39a470dd579..6642d3a1caf 100644
--- a/tfjs-backend-wasm/rollup.config.js
+++ b/tfjs-backend-wasm/rollup.config.js
@@ -44,7 +44,7 @@ function config({plugins = [], output = {}}) {
       typescript({
         tsconfigOverride: {compilerOptions: {module: 'ES2015'}},
       }),
-      node(),
+      node({preferBuiltins: true}),
       // Polyfill require() from dependencies.
       commonjs({
         ignore: ['crypto', 'node-fetch', 'util'],
@@ -55,10 +55,10 @@ function config({plugins = [], output = {}}) {
     output: {
       banner: PREAMBLE,
       sourcemap: true,
-      globals: {'@tensorflow/tfjs-core': 'tf'},
+      globals: {'@tensorflow/tfjs-core': 'tf', 'fs': 'fs', 'path': 'path'},
       ...output,
     },
-    external: ['crypto', '@tensorflow/tfjs-core'],
+    external: ['crypto', '@tensorflow/tfjs-core', 'fs', 'path'],
     onwarn: warning => {
       let {code} = warning;
       if (code === 'CIRCULAR_DEPENDENCY' || code === 'CIRCULAR' ||
diff --git a/tfjs-backend-wasm/src/kernels/Slice.ts b/tfjs-backend-wasm/src/kernels/Slice.ts
index 91ed047adf5..df91fdc65bb 100644
--- a/tfjs-backend-wasm/src/kernels/Slice.ts
+++ b/tfjs-backend-wasm/src/kernels/Slice.ts
@@ -29,7 +29,7 @@ interface SliceAttrs extends NamedAttrMap {
   size: number[];
 }
 
-function slice(
+export function slice(
     args: {inputs: SliceInputs, attrs: SliceAttrs, backend: BackendWasm}) {
   const {inputs: {x}, attrs: {begin, size}, backend} = args;
   const isContinous = slice_util.isSliceContinous(x.shape, begin, size);
diff --git a/tfjs-backend-wasm/src/kernels/Unpack.ts b/tfjs-backend-wasm/src/kernels/Unpack.ts
new file mode 100644
index 00000000000..25d6659e01c
--- /dev/null
+++ b/tfjs-backend-wasm/src/kernels/Unpack.ts
@@ -0,0 +1,58 @@
+/**
+ * @license
+ * Copyright 2019 Google Inc. All Rights Reserved.
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ * =============================================================================
+ */
+
+import {NamedAttrMap, NamedTensorInfoMap, registerKernel, TensorInfo} from '@tensorflow/tfjs-core';
+import {BackendWasm} from '../backend_wasm';
+import {slice} from './Slice';
+
+interface UnpackInputs extends NamedTensorInfoMap {
+  x: TensorInfo;
+}
+
+interface UnpackAttrs extends NamedAttrMap {
+  axis: number;
+}
+
+function unpack(
+    args: {inputs: UnpackInputs, backend: BackendWasm, attrs: UnpackAttrs}):
+    TensorInfo[] {
+  const {inputs: {x}, backend, attrs: {axis}} = args;
+  const numOutputs = x.shape[axis];
+  const rank = x.shape.length;
+  const outShape: number[] = new Array(rank - 1);
+  let outIndex = 0;
+  for (let i = 0; i < rank; i++) {
+    if (i !== axis) {
+      outShape[outIndex++] = x.shape[i];
+    }
+  }
+  const outs: TensorInfo[] = new Array(numOutputs);
+  const begin = new Array(rank).fill(0);
+  const size = x.shape.slice();
+  size[axis] = 1;
+  for (let i = 0; i < outs.length; i++) {
+    begin[axis] = i;
+    outs[i] = slice({inputs: {x}, attrs: {begin, size}, backend});
+  }
+  return outs.map(({dataId, dtype}) => ({dataId, dtype, shape: outShape}));
+}
+
+registerKernel({
+  kernelName: 'Unpack',
+  backendName: 'wasm',
+  kernelFunc: unpack,
+});
diff --git a/tfjs-backend-wasm/src/kernels/all_kernels.ts b/tfjs-backend-wasm/src/kernels/all_kernels.ts
index 51819c27127..3360c73762b 100644
--- a/tfjs-backend-wasm/src/kernels/all_kernels.ts
+++ b/tfjs-backend-wasm/src/kernels/all_kernels.ts
@@ -52,3 +52,4 @@ import './Slice';
 import './Square';
 import './Sub';
 import './Transpose';
+import './Unpack';
diff --git a/tfjs-backend-wasm/src/setup_test.ts b/tfjs-backend-wasm/src/setup_test.ts
index bcc0d59483e..8a4da9c7301 100644
--- a/tfjs-backend-wasm/src/setup_test.ts
+++ b/tfjs-backend-wasm/src/setup_test.ts
@@ -194,6 +194,7 @@ const TEST_FILTERS: TestFilter[] = [
   {include: 'nonMaxSuppression'},
   {include: 'argmax', excludes: ['gradient']},
   {include: 'exp '},
+  {include: 'unstack'},
 ];
 
 const customInclude = (testName: string) => {
diff --git a/tfjs-core/src/ops/array_ops.ts b/tfjs-core/src/ops/array_ops.ts
index 58a21f9cd4c..1b976b726d1 100644
--- a/tfjs-core/src/ops/array_ops.ts
+++ b/tfjs-core/src/ops/array_ops.ts
@@ -26,70 +26,60 @@ import {op} from './operation';
 import {MPRandGauss, RandGamma, UniformRandom} from './rand';
 import {zeros, zerosLike} from './tensor_ops';
 
-/** Broadcast an array to a compatible shape NumPy-style.
- *  
- *  The tensor's shape is compared to the broadcast shape from end to beginning.
- *  Ones are prepended to the tensor's shape until is has the same length as
- *  the broadcast shape. If input.shape[i]==shape[i], the (i+1)-th axis is
- *  already broadcast-compatible. If input.shape[i]==1 and shape[i]==N, then
- *  the input tensor is tiled N times along that axis (using tf.tile).
- *  
- *  @param input The tensor that is to be broadcasted.
- *  @param shape The input is to be broadcast to this shape.
+/**
+ * Broadcast an array to a compatible shape NumPy-style.
+ *
+ * The tensor's shape is compared to the broadcast shape from end to beginning.
+ * Ones are prepended to the tensor's shape until is has the same length as
+ * the broadcast shape. If input.shape[i]==shape[i], the (i+1)-th axis is
+ * already broadcast-compatible. If input.shape[i]==1 and shape[i]==N, then
+ * the input tensor is tiled N times along that axis (using tf.tile).
+ *
+ * @param input The tensor that is to be broadcasted.
+ * @param shape The input is to be broadcast to this shape.
  */
 /** @doc {heading: 'Tensors', subheading: 'Transformations'} */
 function broadcastTo_<R extends Rank>(
-  x: Tensor|TensorLike, shape: ShapeMap[R]
-): Tensor<R>
-{
+    x: Tensor|TensorLike, shape: ShapeMap[R]): Tensor<R> {
   let input = convertToTensor(x, 'broadcastTo', 'x');
   const xShape = input.shape;
 
-  if( shape.some(d => !(d > 0) || d%1 !== 0) ) {
+  if (shape.some(d => !(d > 0) || d % 1 !== 0)) {
     throw new Error(`broadcastTo(): Invalid broadcast shape [${shape}].`);
   }
 
-  if( shape.length < input.rank ) {
-    throw new Error(
-      `broadcastTo(): shape.length=${shape.length} < input.rank=${input.rank}.`
-    );
+  if (shape.length < input.rank) {
+    throw new Error(`broadcastTo(): shape.length=${shape.length} < input.rank=${
+        input.rank}.`);
   }
 
-  if( shape.length > input.rank )
-  {
-    const newShape =  input.shape.slice();
-    while(newShape.length < shape.length ) {
-          newShape.unshift(1);
+  if (shape.length > input.rank) {
+    const newShape = input.shape.slice();
+    while (newShape.length < shape.length) {
+      newShape.unshift(1);
     }
     input = input.reshape(newShape);
   }
 
   const reps: number[] = Array.from(shape);
-  for( let i=shape.length-1; i >= 0; i-- )
-  {
-    if( input.shape[i] === shape[i] ) {
+  for (let i = shape.length - 1; i >= 0; i--) {
+    if (input.shape[i] === shape[i]) {
       reps[i] = 1;
-    }
-    else if( input.shape[i] !== 1 ) {
+    } else if (input.shape[i] !== 1) {
       throw new Error(
-        `broadcastTo(): [${xShape}] cannot be broadcast to [${shape}].`
-      );
+          `broadcastTo(): [${xShape}] cannot be broadcast to [${shape}].`);
     }
   }
+  const axes = reps.map((n, i) => n > 1 ? i : -1).filter(i => i >= 0);
 
-  const axes = reps.map( ( n,i)  => n > 1 ? i : -1 ).filter( i => i >= 0 );
-
-  if( axes.length === 0 ) {
+  if (axes.length === 0) {
     return input.clone() as Tensor<R>;
   }
 
   return ENGINE.runKernelFunc(
-    backend => backend.tile(input,reps),
-    {input},
-    (dy: Tensor) => ({
-      input: () => dy.sum(axes,/*keepDims=*/true)
-    })
-  ) as Tensor<R>;
+             backend => backend.tile(input, reps), {input},
+             (dy: Tensor) =>
+                 ({input: () => dy.sum(axes, /*keepDims=*/true)})) as Tensor<R>;
 }
 
 /**
@@ -917,9 +907,11 @@ function unstack_(x: Tensor|TensorLike, axis = 0): Tensor[] {
     axis += $x.shape.length;
   }
   const grad = (dy: Tensor[]) => {
-    return {$x: () => stack(dy, axis)};
+    return {x: () => stack(dy, axis)};
   };
-  return ENGINE.runKernelFunc(backend => backend.unstack($x, axis), {$x}, grad);
+  const attrs = {axis};
+  return ENGINE.runKernelFunc(
+      backend => backend.unstack($x, axis), {x: $x}, grad, 'Unpack', attrs);
 }
 
 /**