diff --git a/tools/ota_analysis/src/components/BasicInfo.vue b/tools/ota_analysis/src/components/BasicInfo.vue
index 6c1e36816..bd751d218 100644
--- a/tools/ota_analysis/src/components/BasicInfo.vue
+++ b/tools/ota_analysis/src/components/BasicInfo.vue
@@ -34,7 +34,7 @@
       <li>
         <strong> Incremental </strong>
         <!-- Check if the first partition is incremental or not -->
-        <span v-if="payload.manifest.partitions[0].oldPartitionInfo">
+        <span v-if="payload.preBuild">
           &#9989;
         </span>
         <span v-else> &#10060; </span>
@@ -44,6 +44,13 @@
         <span v-if="payload.manifest.partialUpdate"> &#9989; </span>
         <span v-else> &#10060; </span>
       </li>
+      <li>
+        <strong> A/B update </strong>
+        <span v-if="!payload.manifest.nonAB">
+          &#9989;
+        </span>
+        <span v-else> &#10060; </span>
+      </li>
       <li>
         <strong> VAB </strong>
         <span v-if="payload.manifest.dynamicPartitionMetadata.snapshotEnabled">
diff --git a/tools/ota_analysis/src/components/OperationDetail.vue b/tools/ota_analysis/src/components/OperationDetail.vue
index 9ce9cf0bf..a40c2159c 100644
--- a/tools/ota_analysis/src/components/OperationDetail.vue
+++ b/tools/ota_analysis/src/components/OperationDetail.vue
@@ -1,6 +1,6 @@
 <template>
   <ul>
-    <h5> {{ mapType.get(operation.type) }} </h5>
+    <h5> {{ mapType.getWithDefault(operation.type) }} </h5>
     <li v-if="operation.hasOwnProperty('dataOffset')">
       <strong> Data offset: </strong> {{ operation.dataOffset }}
     </li>
@@ -25,6 +25,7 @@
 
 <script>
 import { numBlocks, displayBlocks } from '../services/payload_composition.js'
+import { DefaultMap } from '../services/payload.js'
 
 export default {
   props: {
@@ -33,7 +34,7 @@ export default {
       required: true,
     },
     mapType: {
-      type: Map,
+      type: DefaultMap,
       required: true,
     },
   },
diff --git a/tools/ota_analysis/src/components/PartitionDetail.vue b/tools/ota_analysis/src/components/PartitionDetail.vue
index 6a64448dd..778724929 100644
--- a/tools/ota_analysis/src/components/PartitionDetail.vue
+++ b/tools/ota_analysis/src/components/PartitionDetail.vue
@@ -3,9 +3,6 @@
   <p v-if="partition.estimateCowSize">
     <strong> Estimate COW Size: </strong> {{ partition.estimateCowSize }} Bytes
   </p>
-  <p v-else>
-    <strong> Estimate COW Size: </strong> 0 Bytes
-  </p>
   <div
     class="toggle"
     @click="toggle('showInfo')"
@@ -30,7 +27,7 @@
         </strong>
         {{ partition.newPartitionInfo.size }} Bytes
       </li>
-      <li>
+      <li v-if="partition.newPartitionInfo.hash">
         <strong>
           New Partition Hash:
         </strong>
diff --git a/tools/ota_analysis/src/components/PayloadComposition.vue b/tools/ota_analysis/src/components/PayloadComposition.vue
index 587442b5d..5557c734c 100644
--- a/tools/ota_analysis/src/components/PayloadComposition.vue
+++ b/tools/ota_analysis/src/components/PayloadComposition.vue
@@ -37,6 +37,7 @@
       md="6"
     >
       <v-btn
+        :disabled="manifest.nonAB"
         block
         @click="updateChart('COWmerge')"
       >
diff --git a/tools/ota_analysis/src/components/PayloadDetail.vue b/tools/ota_analysis/src/components/PayloadDetail.vue
index 15bb93705..7fbb5cd2e 100644
--- a/tools/ota_analysis/src/components/PayloadDetail.vue
+++ b/tools/ota_analysis/src/components/PayloadDetail.vue
@@ -28,11 +28,11 @@
       </v-col>
     </v-row>
     <v-divider />
-    <h3>Metadata Signature</h3>
     <div
-      v-if="payload.metadata_signature"
+      v-if="payload.metadata_signature && !payload.manifest.nonAB"
       class="signature"
     >
+      <h3>Metadata Signature</h3>
       <span style="white-space: pre-wrap">
         {{ octToHex(payload.metadata_signature.signatures[0].data) }}
       </span>
diff --git a/tools/ota_analysis/src/services/payload.js b/tools/ota_analysis/src/services/payload.js
index 2eaea2d5d..2282a1797 100644
--- a/tools/ota_analysis/src/services/payload.js
+++ b/tools/ota_analysis/src/services/payload.js
@@ -9,6 +9,7 @@
 
 import * as zip from '@zip.js/zip.js/dist/zip-full.min.js'
 import { chromeos_update_engine as update_metadata_pb } from './update_metadata_pb.js'
+import { PayloadNonAB } from './payload_nonab.js'
 
 const /** String */ _MAGIC = 'CrAU'
 const /** Number */ _VERSION_SIZE = 8
@@ -134,8 +135,17 @@ export class Payload {
       }
     }
     if (!this.payload) {
-      alert('Please select a legit OTA package')
-      return
+      try {
+        // The temporary variable manifest has to be used here, to prevent the html page
+        // being rendered before everything is read in properly
+        let manifest = new PayloadNonAB(this.packedFile)
+        await manifest.init()
+        manifest.nonAB = true
+        this.manifest = manifest
+      } catch (error) {
+        alert('Please select a legit OTA package')
+        return
+      }
     }
   }
 
@@ -208,6 +218,7 @@ export class Payload {
     this.cursor += this.manifest_len
     this.manifest = update_metadata_pb.DeltaArchiveManifest
       .decode(new Uint8Array(buffer))
+    this.manifest.nonAB = false
   }
 
   async readSignature(/** @type {Blob} */buffer) {
@@ -235,6 +246,17 @@ export class Payload {
 
 }
 
+export class DefaultMap extends Map {
+  /** Reload the original get method. Return the original key value if
+   * the key does not exist.
+   * @param {Any} key
+   */
+  getWithDefault(key) {
+    if (!this.has(key)) return key
+    return this.get(key)
+  }
+}
+
 export class OpType {
   /**
    * OpType.mapType create a map that could resolve the operation
@@ -243,8 +265,8 @@ export class OpType {
    */
   constructor() {
     let /** Array<{String: Number}>*/ types = update_metadata_pb.InstallOperation.Type
-    this.mapType = new Map()
-    for (let key in types) {
+    this.mapType = new DefaultMap()
+    for (let key of Object.keys(types)) {
       this.mapType.set(types[key], key)
     }
   }
@@ -259,8 +281,8 @@ export class MergeOpType {
   constructor() {
     let /** Array<{String: Number}>*/ types =
       update_metadata_pb.CowMergeOperation.Type
-    this.mapType = new Map()
-    for (let key in types) {
+    this.mapType = new DefaultMap()
+    for (let key of Object.keys(types)) {
       this.mapType.set(types[key], key)
     }
   }
diff --git a/tools/ota_analysis/src/services/payload_composition.js b/tools/ota_analysis/src/services/payload_composition.js
index 08005356d..6db8a0a34 100644
--- a/tools/ota_analysis/src/services/payload_composition.js
+++ b/tools/ota_analysis/src/services/payload_composition.js
@@ -34,7 +34,7 @@ export function operatedBlockStatistics(partitions) {
   let /** OpType */ opType = new OpType()
   for (let partition of partitions) {
     for (let operation of partition.operations) {
-      let operationType = opType.mapType.get(operation.type)
+      let operationType = opType.mapType.getWithDefault(operation.type)
       addNumberToMap(
         operatedBlocks,
         operationType,
@@ -50,7 +50,7 @@ export function mergeOperationStatistics(partitions, blockSize) {
   let /** Number */ totalBlocks = 0
   for (let partition of partitions) {
     for (let operation of partition.mergeOperations) {
-      let operationType = opType.mapType.get(operation.type)
+      let operationType = opType.mapType.getWithDefault(operation.type)
       addNumberToMap(
         mergeOperations,
         operationType,
@@ -79,7 +79,7 @@ export function operatedPayloadStatistics(partitions) {
   let /** OpType */ opType = new OpType()
   for (let partition of partitions) {
     for (let operation of partition.operations) {
-      let operationType = opType.mapType.get(operation.type)
+      let operationType = opType.mapType.getWithDefault(operation.type)
       addNumberToMap(
         operatedBlocks,
         operationType,
diff --git a/tools/ota_analysis/src/services/payload_nonab.js b/tools/ota_analysis/src/services/payload_nonab.js
new file mode 100644
index 000000000..5f43401a1
--- /dev/null
+++ b/tools/ota_analysis/src/services/payload_nonab.js
@@ -0,0 +1,145 @@
+import * as zip from '@zip.js/zip.js/dist/zip-full.min.js'
+import { chromeos_update_engine } from './update_metadata_pb.js'
+
+/**
+ * Parse the non-A/B OTA package and return it as a DeltaArchiveManifest
+ * @param {ZipReader} packedFile
+ */
+export class PayloadNonAB extends chromeos_update_engine.DeltaArchiveManifest{
+  constructor(packedFile) {
+    super()
+    this.packedFile = packedFile
+  }
+
+  async init() {
+    this.Blocksize = 4096
+    this.partialUpdate = false
+    this.dynamicPartitionMetadata =
+      new chromeos_update_engine.DynamicPartitionMetadata(
+        { snapshotEnabled: false, vabcEnabled: false }
+      )
+    this.partitions = []
+
+    const /** RegExp*/ regexName = /[\w_]+(?=\.transfer.list)/g
+    const /** Array<Entry> */ entries = await this.packedFile.getEntries()
+    for (const entry of entries) {
+      if (entry.filename.match(regexName)) {
+        let newPartition = new chromeos_update_engine.PartitionUpdate(
+          {partitionName: entry.filename.match(regexName)[0]}
+        )
+        newPartition.rawText = await entry.getData(new zip.TextWriter())
+        await this.parseTransferList(newPartition)
+        this.partitions.push(newPartition)
+      }
+    }
+  }
+
+  async parseTransferList(partition) {
+    let /** Array<String> */ lines = partition.rawText.split('\n')
+    // First four line in header: version, total blocks,
+    // number of stashed entries, maximum used memory for stash
+    if (lines.length < 4) {
+      throw "At least 4 lines in header should be provided."
+    }
+    partition.version = parseInt(lines[0])
+    partition.totalBlocks = parseInt(lines[1])
+    partition.entryStashed = parseInt(lines[2])
+    partition.maxStashed = parseInt(lines[3])
+    partition.newPartitionInfo = new chromeos_update_engine.PartitionInfo()
+    partition.newPartitionInfo.hash = ''
+    partition.newPartitionInfo.size = 'unknown'
+    /**
+    * The main body have 8 different ops:
+    * zero [rangeset] : fill zeros
+    * new [rangeset] : fill with new data from <partitionName.new.data>
+    * erase [rangeset] : mark given blocks as empty
+    * move <...>
+    * bsdiff <patchstart> <patchlen> <...>
+    * imgdiff <patchstart> <patchlen> <...> :
+    * Read the source blocks and apply (not for move op) to the target blocks
+    * stash <stash_id> <src_range> : load the given source range to memory
+    * free <stash_id> : free the given <stash_id>
+    * format:
+    * [rangeset]: <# of pairs>, <pair A start>, <pair A end>, ...
+    * <stash_id>: a hex number with length of 40
+    */
+    partition.operations = new Array()
+    let newDataSize = await this.sizeNewData(partition.partitionName)
+    for (const line of lines.slice(4)) {
+      let op = new chromeos_update_engine.InstallOperation()
+      let elements = line.split(' ')
+      op.type = elements[0]
+      switch (op.type) {
+      case 'zero':
+        op.dstExtents = elements.slice(1).reduce(parseRange, [])
+        break
+      case 'new':
+        // unlike an A/B OTA, the payload only exists in the payload.bin,
+        // in an non-A/B OTA, the payload exists in both .new.data and .patch.data.
+        // The new ops do not have any information about data length.
+        // what we do here is: read in the size of .new.data, assume the first new
+        // op have the data length of the size of .new.data.
+        op.dataLength = newDataSize
+        newDataSize = 0
+        op.dstExtents = elements.slice(1).reduce(parseRange, [])
+        break
+      case 'erase':
+        op.dstExtents = elements.slice(1).reduce(parseRange, [])
+        break
+      case 'move':
+        break
+      case 'bsdiff':
+        op.dataOffset = parseInt(elements[1])
+        op.dataLength = parseInt(elements[2])
+        break
+      case 'imgdiff':
+        op.dataOffset = parseInt(elements[1])
+        op.dataLength = parseInt(elements[2])
+        break
+      case 'stash':
+        break
+      case 'free':
+        break
+      }
+      partition.operations.push(op)
+    }
+  }
+
+  /**
+   * Return the size of <partitionName>.new.data.*
+   * @param {String} partitionName
+   * @return {Number}
+   */
+  async sizeNewData(partitionName) {
+    const /** Array<Entry> */ entries = await this.packedFile.getEntries()
+    const /** RegExp */ regexName = new RegExp(partitionName + '.new.dat.*')
+    for (const entry of entries) {
+      if (entry.filename.match(regexName)) {
+        return entry.uncompressedSize
+      }
+    }
+  }
+}
+
+/**
+ * Parse the range string and return it as an array of extents
+ * @param {extents} Array<extents>
+ * @param {String} rangeset
+ * @return Array<extents>
+ */
+function parseRange(extents, rangeset) {
+  const regexRange = new RegExp('[\d,]+')
+  if (rangeset.match(regexRange)) {
+    let elements = rangeset.split(',')
+    for (let i=1; i<elements.length; i=i+2) {
+      let extent = new Object(
+        {
+          startBlock: parseInt(elements[i]),
+          numBlocks: parseInt(elements[i+1]) - parseInt(elements[i])
+        }
+      )
+      extents.push(extent)
+    }
+  }
+  return extents
+}
\ No newline at end of file