diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/Action.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/Action.java
index 834994e..13a1cc9 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/Action.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/Action.java
@@ -92,14 +92,14 @@
     return "?";
   }
 
-  private List<String> getOwners(OwnersDb db, Collection<String> files) {
+  private List<OwnerInfo> getOwners(OwnersDb db, Collection<String> files) {
     Map<String, OwnerWeights> weights = new HashMap<>();
     db.findOwners(files, weights);
-    List<String> result = new ArrayList<>();
+    List<OwnerInfo> result = new ArrayList<>();
     Set<String> emails = new HashSet<>();
     for (String key : OwnerWeights.sortKeys(weights)) {
       if (!emails.contains(key)) {
-        result.add(key + " " + weights.get(key).encodeLevelCounts());
+        result.add(new OwnerInfo(key, weights.get(key).getLevelCounts()));
         emails.add(key);
       }
     }
@@ -136,7 +136,7 @@
     try {
       for (Account.Id id : changeData.reviewers().all()) {
         Account account = accountCache.get(id).getAccount();
-        result.add(account.getPreferredEmail() + " []");
+        result.add(account.getPreferredEmail());
       }
     } catch (OrmException e) {
       log.error("Exception", e);
diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnerInfo.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnerInfo.java
new file mode 100644
index 0000000..72894d0
--- /dev/null
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnerInfo.java
@@ -0,0 +1,28 @@
+// Copyright (C) 2017 The Android Open Source Project
+//
+// 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.
+
+package com.googlesource.gerrit.plugins.findowners;
+
+import java.util.List;
+
+/** Keeps owner email and weights. */
+public class OwnerInfo {
+  OwnerInfo(String e, List<Integer> w) {
+    email = e;
+    weights = w;
+  }
+
+  String email;
+  List<Integer> weights;
+}
diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnerWeights.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnerWeights.java
index d57304b..233f1d2 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnerWeights.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/OwnerWeights.java
@@ -14,6 +14,7 @@
 
 package com.googlesource.gerrit.plugins.findowners;
 
+import com.google.common.collect.ImmutableList;
 import java.util.ArrayList;
 import java.util.Collections;
 import java.util.Comparator;
@@ -64,6 +65,11 @@
     return "[" + countL1 + "+" + countL2 + "+" + countL3 + "]";
   }
 
+  /** Return file counters as a list of integers. */
+  List<Integer> getLevelCounts() {
+    return ImmutableList.of(countL1, countL2, countL3);
+  }
+
   OwnerWeights(String file, int level) {
     addFile(file, level);
   }
diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/RestResult.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/RestResult.java
index b0b227c..f91ecbe 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/RestResult.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/RestResult.java
@@ -35,9 +35,9 @@
   String ownerRevision;
 
   DebugMessages dbgmsgs;
-  SortedMap<String, String> file2owners = new TreeMap<>();
+  SortedMap<String, List<String>> file2owners = new TreeMap<>();
   List<String> reviewers = new ArrayList<>();
-  List<String> owners = new ArrayList<>();
+  List<OwnerInfo> owners = new ArrayList<>();
   List<String> files = new ArrayList<>();
 
   RestResult(int voteLevel, boolean addDebugMsg) {
@@ -54,7 +54,7 @@
     String user;
     String project;
     String branch;
-    SortedMap<String, String> path2owners;
-    SortedMap<String, String> owner2paths;
+    SortedMap<String, List<String>> path2owners;
+    SortedMap<String, List<String>> owner2paths;
   };
 }
diff --git a/src/main/java/com/googlesource/gerrit/plugins/findowners/Util.java b/src/main/java/com/googlesource/gerrit/plugins/findowners/Util.java
index 76a0e53..1888fa1 100644
--- a/src/main/java/com/googlesource/gerrit/plugins/findowners/Util.java
+++ b/src/main/java/com/googlesource/gerrit/plugins/findowners/Util.java
@@ -17,6 +17,7 @@
 import com.google.common.collect.Ordering;
 import java.io.File;
 import java.util.HashSet;
+import java.util.List;
 import java.util.Map;
 import java.util.Set;
 import java.util.SortedMap;
@@ -46,10 +47,10 @@
     return (s != null) && (s.equals("1") || s.equalsIgnoreCase("yes") || Boolean.parseBoolean(s));
   }
 
-  static SortedMap<String, String> makeSortedMap(Map<String, Set<String>> map) {
-    SortedMap<String, String> result = new TreeMap<>();
+  static SortedMap<String, List<String>> makeSortedMap(Map<String, Set<String>> map) {
+    SortedMap<String, List<String>> result = new TreeMap<>();
     for (String key : Ordering.natural().sortedCopy(map.keySet())) {
-      result.put(key, String.join(" ", Ordering.natural().sortedCopy(map.get(key))));
+      result.put(key, Ordering.natural().sortedCopy(map.get(key)));
     }
     return result;
   }
diff --git a/src/main/resources/Documentation/rest-api.md b/src/main/resources/Documentation/rest-api.md
index 34152d3..7676059 100644
--- a/src/main/resources/Documentation/rest-api.md
+++ b/src/main/resources/Documentation/rest-api.md
@@ -52,28 +52,29 @@
 
     * **project**: the change's project name.
 
-    * **branch**: the change's destination brach name.
+    * **branch**: the change's destination branch name.
 
     * **path2owners**:
-      a map from directory path or file glob to a string of owner emails
-      separated by space. Note that `*` is a special owner email address.
+      a map from directory path or file glob to an array of owner emails.
+      Note that `*` is a special owner email address.
       It means that there is no owner and anyone can be the owner.
       Included directories are those affected by the change revision.
 
     * **owner2paths**:
-      a map from owner email to directory path or file glob.
+      a map from owner email to an array of directory path or file glob.
       This is opposite to the path2owners map.
 
-* **file2owners**: a map from each file in the change patchset to
-   the file owner emails, separated by space.
+* **file2owners**: a map from each file path in the change patchset to
+   an array of the file's owner emails.
 
-* **reviewers**: an array of current reviewer emails followed by
-   optional extra information that should be ignored for now.
+* **reviewers**: an array of current reviewer emails.
 
-* **owners**: an array of owner emails followed by the owner weights,
-   `[n1+n2+n3]`, which are the number of level 1, 2, 3+ controlled files.
-   This list of owners are the keys in the owner2paths map.
-   The array is sorted by owner weights.
+* **owners**: an array of owner info objects.
+   Each owner info object has "email" and "weights" attributes.
+   The weights attribute is an array of integers like [n1, n2, n3],
+   which are the number of level 1, 2, 3+ controlled files.
+   The email attributes are the keys in the owner2paths map.
+   This owners array is sorted by owner weights.
    Users should try to pick owners with more weights to review a change.
 
 * **files**: an alphabetically sorted files changed
diff --git a/src/main/resources/static/find-owners.js b/src/main/resources/static/find-owners.js
index 94d303f..8122474 100644
--- a/src/main/resources/static/find-owners.js
+++ b/src/main/resources/static/find-owners.js
@@ -176,7 +176,7 @@
     }
     function showFilesAndOwners(result, args) {
       var sortedOwners = result.owners.map(
-          function(line) { return line.split(' ')[0]; });
+          function(ownerInfo) { return ownerInfo.email; });
       var groups = {};
       // group name ==> {needReviewer, needApproval, owners}
       var groupSize = {};
@@ -249,7 +249,7 @@
           div.appendChild(nobr);
         }
         keys.forEach(function(key) {
-          var owners = groups[key].owners;
+          var owners = groups[key].owners; // string of owner emails
           var numFiles = groupSize[key];
           var item = HTML_BULLET + '&nbsp;<b>' + key + '</b>' +
               ((numFiles > 1) ? (' (' + numFiles + ' files):') : ':');
@@ -269,8 +269,11 @@
         div.innerHTML = '';
         div.style.display = 'inline';
         div.appendChild(strElement(title));
-        result.owners.sort().forEach(function(owner) {
-          var email = owner.split(' ')[0];
+        function compareOwnerInfo(o1, o2) {
+          return o1.email.localeCompare(o2.email);
+        }
+        result.owners.sort(compareOwnerInfo).forEach(function(ownerInfo) {
+          var email = ownerInfo.email;
           var vote = reviewerVote[email];
           if ((email in reviewerVote) && vote != 0) {
             email += ' <font color="' +
@@ -309,8 +312,8 @@
             ('minOwnerVoteLevel' in result ?
              result['minOwnerVoteLevel'] : 1);
         Object.keys(result.file2owners).sort().forEach(function(name) {
-          var owners = result.file2owners[name];
-          var splitOwners = owners.split(' ');
+          var splitOwners = result.file2owners[name];
+          var owners = splitOwners.join(' ');
           if (owners in owners2group) {
             groupSize[owners2group[owners]] += 1;
           } else {
diff --git a/src/test/java/com/googlesource/gerrit/plugins/findowners/FindOwnersIT.java b/src/test/java/com/googlesource/gerrit/plugins/findowners/FindOwnersIT.java
index c8b3b3e..11274c6 100644
--- a/src/test/java/com/googlesource/gerrit/plugins/findowners/FindOwnersIT.java
+++ b/src/test/java/com/googlesource/gerrit/plugins/findowners/FindOwnersIT.java
@@ -79,15 +79,20 @@
     assertThat(getOwnersResponse(c2)).contains("owners:[], files:[ t.c ]");
     // Change of "t.c" file has owner after c1 is submitted.
     approveSubmit(c1);
-    assertThat(getOwnersResponse(c2)).contains("owners:[ a@a[1+0+0], x@x[1+0+0] ], files:[ t.c ]");
+    String ownerA = ownerJson("a@a");
+    String ownerB = ownerJson("b@b");
+    String ownerC = ownerJson("c@c");
+    String ownerX = ownerJson("x@x");
+    String ownersAX = "owners:[ " + ownerA + ", " + ownerX + " ]";
+    assertThat(getOwnersResponse(c2)).contains(ownersAX + ", files:[ t.c ]");
     // A submitted change gets owners info from current repository.
-    assertThat(getOwnersResponse(c1))
-        .contains("owners:[ a@a[1+0+0], x@x[1+0+0] ], files:[ OWNERS ]");
+    assertThat(getOwnersResponse(c1)).contains(ownersAX + ", files:[ OWNERS ]");
     // Check all fields in response.
     String expectedTail =
-        "path2owners:{ ./:a@ax@x }, owner2paths:{ a@a:./, x@x:./ } }"
-            + ", file2owners:{ ./t.c:a@ax@x }, reviewers:[], owners:[ "
-            + "a@a[1+0+0], x@x[1+0+0] ], files:[ t.c ] }";
+        "path2owners:{ ./:[ a@a, x@x ] }, owner2paths:{ a@a:[ ./ ], x@x:[ ./ ] } }"
+            + ", file2owners:{ ./t.c:[ a@a, x@x ] }, reviewers:[], "
+            + ownersAX
+            + ", files:[ t.c ] }";
     assertThat(getOwnersDebugResponse(c2)).contains(expectedTail);
   }
 
@@ -97,11 +102,15 @@
     addFile("add OWNERS", "OWNERS", "per-file *.c=x@x\na@a\nc@c\nb@b\n");
     // Add "t.c" file, which has per-file owner x@x, not a@a, b@b, c@c.
     PushOneCommit.Result c2 = createChange("add t.c", "t.c", "Hello!");
-    assertThat(getOwnersResponse(c2)).contains("owners:[ x@x[1+0+0] ], files:[ t.c ]");
+    String ownerA = ownerJson("a@a");
+    String ownerB = ownerJson("b@b");
+    String ownerC = ownerJson("c@c");
+    String ownerX = ownerJson("x@x");
+    assertThat(getOwnersResponse(c2)).contains("owners:[ " + ownerX + " ], files:[ t.c ]");
     // Add "t.txt" file, which has new owners.
     PushOneCommit.Result c3 = createChange("add t.txt", "t.txt", "Test!");
     assertThat(getOwnersResponse(c3))
-        .contains("owners:[ a@a[1+0+0], b@b[1+0+0], c@c[1+0+0] ], files:[ t.txt ]");
+        .contains("owners:[ " + ownerA + ", " + ownerB + ", " + ownerC + " ], files:[ t.txt ]");
   }
 
   @Test
@@ -113,25 +122,30 @@
     addFile("add d3/OWNERS", "d3/OWNERS", "b@b\nset noparent\n");
     // Add "t.c" file, which is not owned by subdirectory owners.
     PushOneCommit.Result c2 = createChange("add t.c", "t.c", "Hello!");
-    assertThat(getOwnersResponse(c2)).contains("owners:[ x@x[1+0+0] ], files:[ t.c ]");
+    String ownerA = ownerJson("a@a");
+    String ownerX = ownerJson("x@x");
+    assertThat(getOwnersResponse(c2)).contains("owners:[ " + ownerX + " ], files:[ t.c ]");
     // Add "d1/t.c" file, which is owned by ./d1 and root owners.
     PushOneCommit.Result c3 = createChange("add d1/t.c", "d1/t.c", "Hello!");
+    String ownerX010 = ownerJson("x@x", 0, 1, 0);
     assertThat(getOwnersResponse(c3))
-        .contains("owners:[ a@a[1+0+0], x@x[0+1+0] ], files:[ d1/t.c ]");
+        .contains("owners:[ " + ownerA + ", " + ownerX010 + " ], files:[ d1/t.c ]");
     // Add "d2/t.c" file, which is owned by ./d2 and root owners.
     PushOneCommit.Result c4 = createChange("add d2/t.c", "d2/t.c", "Hello!");
+    String ownerY = ownerJson("y@y");
     assertThat(getOwnersResponse(c4))
-        .contains("owners:[ y@y[1+0+0], x@x[0+1+0] ], files:[ d2/t.c ]");
+        .contains("owners:[ " + ownerY + ", " + ownerX010 + " ], files:[ d2/t.c ]");
     // Add "d2/d1/t.c" file, which is owned by ./d2 and root owners.
     PushOneCommit.Result c5 = createChange("add d2/d1/t.c", "d2/d1/t.c", "Hello!");
     assertThat(getOwnersResponse(c5))
-        .contains("owners:[ y@y[1+0+0], x@x[0+1+0] ], files:[ d2/d1/t.c ]");
+        .contains("owners:[ " + ownerY + ", " + ownerX010 + " ], files:[ d2/d1/t.c ]");
     // Add "d3/t.c" file, which is owned only by ./d3 owners due to "set noparent".
     PushOneCommit.Result c6 = createChange("add d3/t.c", "d3/t.c", "Hello!");
-    assertThat(getOwnersResponse(c6)).contains("owners:[ b@b[1+0+0] ], files:[ d3/t.c ]");
+    String ownerB = ownerJson("b@b");
+    assertThat(getOwnersResponse(c6)).contains("owners:[ " + ownerB + " ], files:[ d3/t.c ]");
     // Add "d3/d1/t.c" file, which is owned only by ./d3 owners due to "set noparent".
     PushOneCommit.Result c7 = createChange("add d3/d1/t.c", "d3/d1/t.c", "Hello!");
-    assertThat(getOwnersResponse(c7)).contains("owners:[ b@b[1+0+0] ], files:[ d3/d1/t.c ]");
+    assertThat(getOwnersResponse(c7)).contains("owners:[ " + ownerB + " ], files:[ d3/d1/t.c ]");
   }
 
   @Test
@@ -212,8 +226,10 @@
     assertThat(Config.getOwnersFileName(pA)).isEqualTo("OWNERS");
     assertThat(Config.getOwnersFileName(pB)).isEqualTo("OWNERS");
 
-    assertThat(getOwnersResponse(cA)).contains("owners:[ x@x[1+0+0] ], files:[ tA.c ]");
-    assertThat(getOwnersResponse(cB)).contains("owners:[ y@y[1+0+0] ], files:[ tB.c ]");
+    String ownerX = oneOwnerList("x@x");
+    String ownerY = oneOwnerList("y@y");
+    assertThat(getOwnersResponse(cA)).contains(ownerX + ", files:[ tA.c ]");
+    assertThat(getOwnersResponse(cB)).contains(ownerY + ", files:[ tB.c ]");
 
     // Change owners file name to "OWNERS.alpha" and "OWNERS.beta"
     switchProject(pA);
@@ -222,21 +238,23 @@
     setProjectConfig("ownersFileName", "OWNERS.beta");
     assertThat(Config.getOwnersFileName(pA)).isEqualTo("OWNERS.alpha");
     assertThat(Config.getOwnersFileName(pB)).isEqualTo("OWNERS.beta");
-    assertThat(getOwnersResponse(cA)).contains("owners:[ a@a[1+0+0] ], files:[ tA.c ]");
-    assertThat(getOwnersResponse(cB)).contains("owners:[ b@b[1+0+0] ], files:[ tB.c ]");
+    String ownerA = oneOwnerList("a@a");
+    String ownerB = oneOwnerList("b@b");
+    assertThat(getOwnersResponse(cA)).contains(ownerA + ", files:[ tA.c ]");
+    assertThat(getOwnersResponse(cB)).contains(ownerB + ", files:[ tB.c ]");
 
     // Change back to OWNERS in Project_A
     switchProject(pA);
     setProjectConfig("ownersFileName", "OWNERS");
     assertThat(Config.getOwnersFileName(pA)).isEqualTo("OWNERS");
-    assertThat(getOwnersResponse(cA)).contains("owners:[ x@x[1+0+0] ], files:[ tA.c ]");
-    assertThat(getOwnersResponse(cB)).contains("owners:[ b@b[1+0+0] ], files:[ tB.c ]");
+    assertThat(getOwnersResponse(cA)).contains(ownerX + ", files:[ tA.c ]");
+    assertThat(getOwnersResponse(cB)).contains(ownerB + ", files:[ tB.c ]");
 
     // Change back to OWNERS.alpha in Project_B, but there is no OWNERS.alpha
     switchProject(pB);
     setProjectConfig("ownersFileName", "OWNERS.alpha");
     assertThat(Config.getOwnersFileName(pB)).isEqualTo("OWNERS.alpha");
-    assertThat(getOwnersResponse(cA)).contains("owners:[ x@x[1+0+0] ], files:[ tA.c ]");
+    assertThat(getOwnersResponse(cA)).contains(ownerX + ", files:[ tA.c ]");
     assertThat(getOwnersResponse(cB)).contains("owners:[], files:[ tB.c ]");
 
     // Do not accept empty string or all-white-spaces for ownersFileName.
@@ -279,6 +297,18 @@
     assertThat(cache.size()).isEqualTo(0);
   }
 
+  private String oneOwnerList(String email) {
+    return "owners:[ " + ownerJson(email) + " ]";
+  }
+
+  private String ownerJson(String email) {
+    return "{ email:" + email + ", weights:[ 1, 0, 0 ] }";
+  }
+
+  private String ownerJson(String email, int w1, int w2, int w3) {
+    return "{ email:" + email + ", weights:[ " + w1 + ", " + w2 + ", " + w3 + " ] }";
+  }
+
   private ChangeInfo newChangeInfo(String subject) throws Exception {
     // should be called with different subject
     ChangeInput in = new ChangeInput();