diff --git a/CHANGES.md b/CHANGES.md
index 33d80cf7e..27a7a3684 100644
--- a/CHANGES.md
+++ b/CHANGES.md
@@ -1,5 +1,6 @@
 # Unreleased
 - [DEPRECATED] This library is now deprecated and will be EOL on Dec 31 2021.
+- [FIXED] Type of `sinceSeq` can be also a `String` besides an `Integer`.
 
 # 2.19.2 (2021-04-07)
 - [NEW] Add migration guide to the newly supported cloudant-java-sdk (coordinates: com.ibm.cloud:cloudant).
diff --git a/cloudant-client/src/main/java/com/cloudant/client/api/Replication.java b/cloudant-client/src/main/java/com/cloudant/client/api/Replication.java
index e758708cb..a60d24a28 100644
--- a/cloudant-client/src/main/java/com/cloudant/client/api/Replication.java
+++ b/cloudant-client/src/main/java/com/cloudant/client/api/Replication.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 IBM Corp. All rights reserved.
+ * Copyright (c) 2015, 2021 IBM Corp. 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
@@ -17,6 +17,7 @@
 import com.cloudant.client.org.lightcouch.ReplicationResult;
 import com.cloudant.client.org.lightcouch.ReplicationResult.ReplicationHistory;
 import com.cloudant.client.org.lightcouch.Replicator;
+import com.google.gson.JsonParser;
 
 import java.util.Map;
 
@@ -172,13 +173,24 @@ public Replication createTarget(Boolean createTarget) {
     }
 
     /**
-     * Starts a replication since an update sequence.
+     * Create or modify a replication since an update sequence using a replication document.
      *
      * @param sinceSeq sequence number
      * @return this Replication instance to set more options or trigger the replication
      */
     public Replication sinceSeq(Integer sinceSeq) {
-        this.replication = replication.sinceSeq(sinceSeq);
+        this.replication = replication.sinceSeq(new JsonParser().parse(sinceSeq.toString()));
+        return this;
+    }
+
+    /**
+     * Create or modify a replication since an update sequence using a replication document.
+     *
+     * @param sinceSeq sequence string
+     * @return this Replication instance to set more options or trigger the replication
+     */
+    public Replication sinceSeq(String sinceSeq) {
+        this.replication = replication.sinceSeq(new JsonParser().parse(sinceSeq));
         return this;
     }
 
diff --git a/cloudant-client/src/main/java/com/cloudant/client/api/Replicator.java b/cloudant-client/src/main/java/com/cloudant/client/api/Replicator.java
index f2f897ffc..f844e57da 100644
--- a/cloudant-client/src/main/java/com/cloudant/client/api/Replicator.java
+++ b/cloudant-client/src/main/java/com/cloudant/client/api/Replicator.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015, 2019 IBM Corp. All rights reserved.
+ * Copyright (c) 2015, 2021 IBM Corp. 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
@@ -18,6 +18,7 @@
 import com.cloudant.client.org.lightcouch.Replication;
 import com.cloudant.client.org.lightcouch.ReplicatorDocument;
 import com.cloudant.client.org.lightcouch.Response;
+import com.google.gson.JsonParser;
 
 import java.util.ArrayList;
 import java.util.List;
@@ -221,8 +222,25 @@ public Replicator userCtxRoles(String... userCtxRoles) {
         return this;
     }
 
+    /**
+     * Create a transient replication since an update sequence.
+     *
+     * @param sinceSeq sequence number
+     * @return this Replicator instance to set more options or trigger the replication
+     */
     public Replicator sinceSeq(Integer sinceSeq) {
-        this.replicator = replicator.sinceSeq(sinceSeq);
+        this.replicator = replicator.sinceSeq(new JsonParser().parse(sinceSeq.toString()));
+        return this;
+    }
+
+    /**
+     * Create a transient replication since an update sequence.
+     *
+     * @param sinceSeq sequence string
+     * @return this Replicator instance to set more options or trigger the replication
+     */
+    public Replicator sinceSeq(String sinceSeq) {
+        this.replicator = replicator.sinceSeq(new JsonParser().parse(sinceSeq));
         return this;
     }
 
diff --git a/cloudant-client/src/main/java/com/cloudant/client/api/model/ReplicatorDocument.java b/cloudant-client/src/main/java/com/cloudant/client/api/model/ReplicatorDocument.java
index 4b0fddb39..4fb9adef9 100644
--- a/cloudant-client/src/main/java/com/cloudant/client/api/model/ReplicatorDocument.java
+++ b/cloudant-client/src/main/java/com/cloudant/client/api/model/ReplicatorDocument.java
@@ -1,5 +1,5 @@
 /*
- * Copyright (c) 2015 IBM Corp. All rights reserved.
+ * Copyright (c) 2015, 2021 IBM Corp. 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
@@ -16,7 +16,9 @@
 
 import com.cloudant.client.org.lightcouch.Attachment;
 import com.cloudant.client.org.lightcouch.Replicator;
+import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
+import com.google.gson.JsonParser;
 
 import java.util.HashMap;
 import java.util.Map;
@@ -228,11 +230,19 @@ public void setRetriesPerRequest(Integer retriesPerRequest) {
     }
 
     public Integer getSinceSeq() {
-        return replicatorDocument.getSinceSeq();
+        return replicatorDocument.getSinceSeq().getAsInt();
+    }
+
+    public String getSinceSeqString() {
+        return replicatorDocument.getSinceSeq().getAsString();
     }
 
     public void setSinceSeq(Integer sinceSeq) {
-        replicatorDocument.setSinceSeq(sinceSeq);
+        replicatorDocument.setSinceSeq(new JsonParser().parse(sinceSeq.toString()));
+    }
+
+    public void setSinceSeq(String sinceSeq) {
+        replicatorDocument.setSinceSeq(new JsonParser().parse(sinceSeq));
     }
 
     public void setSourceIamApiKey(String iamApiKey) {
diff --git a/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/Replication.java b/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/Replication.java
index 514f99465..a3f07de7a 100644
--- a/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/Replication.java
+++ b/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/Replication.java
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2011 lightcouch.org
- * Copyright (c) 2015 IBM Corp. All rights reserved.
+ * Copyright (c) 2015, 2021 IBM Corp. 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
@@ -19,6 +19,7 @@
 import static com.cloudant.client.org.lightcouch.internal.CouchDbUtil.close;
 
 import com.cloudant.client.internal.DatabaseURIHelper;
+import com.google.gson.JsonElement;
 import com.google.gson.JsonObject;
 
 import java.io.InputStream;
@@ -77,7 +78,7 @@ public class Replication {
     private String[] docIds;
     private String proxy;
     private Boolean createTarget;
-    private Integer sinceSeq;
+    private JsonElement sinceSeq;
 
     // IAM
     private String sourceIamApiKey;
@@ -177,7 +178,7 @@ public Replication createTarget(Boolean createTarget) {
     /**
      * Starts a replication since an update sequence.
      */
-    public Replication sinceSeq(Integer sinceSeq) {
+    public Replication sinceSeq(JsonElement sinceSeq) {
         this.sinceSeq = sinceSeq;
         return this;
     }
diff --git a/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/Replicator.java b/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/Replicator.java
index a17e25841..fefcba689 100644
--- a/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/Replicator.java
+++ b/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/Replicator.java
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2011 lightcouch.org
- * Copyright (c) 2015, 2019 IBM Corp. All rights reserved.
+ * Copyright (c) 2015, 2021 IBM Corp. 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
@@ -274,7 +274,7 @@ public Replicator userCtxRoles(String... userCtxRoles) {
         return this;
     }
 
-    public Replicator sinceSeq(Integer sinceSeq) {
+    public Replicator sinceSeq(JsonElement sinceSeq) {
         replicatorDoc.setSinceSeq(sinceSeq);
         return this;
     }
diff --git a/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/ReplicatorDocument.java b/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/ReplicatorDocument.java
index 5507ae9d2..b98b74734 100644
--- a/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/ReplicatorDocument.java
+++ b/cloudant-client/src/main/java/com/cloudant/client/org/lightcouch/ReplicatorDocument.java
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2011 lightcouch.org
- * Copyright (c) 2015, 2019 IBM Corp. All rights reserved.
+ * Copyright (c) 2015, 2021 IBM Corp. 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
@@ -68,7 +68,7 @@ public class ReplicatorDocument extends Document {
     @SerializedName("user_ctx")
     private UserCtx userCtx;
     @SerializedName("since_seq")
-    private Integer sinceSeq;
+    private JsonElement sinceSeq;
     private JsonElement selector;
 
     public String getSource() {
@@ -268,11 +268,11 @@ public void setRetriesPerRequest(Integer retriesPerRequest) {
         this.retriesPerRequest = retriesPerRequest;
     }
 
-    public Integer getSinceSeq() {
+    public JsonElement getSinceSeq() {
         return sinceSeq;
     }
 
-    public void setSinceSeq(Integer sinceSeq) {
+    public void setSinceSeq(JsonElement sinceSeq) {
         this.sinceSeq = sinceSeq;
     }
 
diff --git a/cloudant-client/src/test/java/com/cloudant/tests/ReplicationTest.java b/cloudant-client/src/test/java/com/cloudant/tests/ReplicationTest.java
index 72885a16b..aa6b5ff54 100644
--- a/cloudant-client/src/test/java/com/cloudant/tests/ReplicationTest.java
+++ b/cloudant-client/src/test/java/com/cloudant/tests/ReplicationTest.java
@@ -1,6 +1,6 @@
 /*
  * Copyright (C) 2011 lightcouch.org
- * Copyright © 2015, 2019 IBM Corp. All rights reserved.
+ * Copyright © 2015, 2021 IBM Corp. 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
@@ -106,4 +106,39 @@ public void replication_conflict() throws Exception {
         //a conflict
         assertConflictsNotZero(db2);
     }
+
+    @Test
+    public void replication_since_seq() throws Exception {
+        String seq = db1.changes().getChanges().getResults().get(2).getSeq();
+        ReplicationResult result = db1Resource.appendReplicationAuth(account.replication()
+            .createTarget(true)
+            .source(db1URI)
+            .target(db2URI)
+            .sinceSeq(seq)
+        )
+            .trigger();
+
+        assertTrue(result.isOk(), "The replication should complete ok");
+
+        List<ReplicationHistory> histories = result.getHistories();
+        assertThat(histories.size(), not(0));
+    }
+
+    @Test
+    public void replication_last_seq() throws Exception {
+        String lastSeq = db1Resource.get().changes().getChanges().getLastSeq();
+
+        ReplicationResult result = db1Resource.appendReplicationAuth(account.replication()
+            .createTarget(true)
+            .source(db1URI)
+            .target(db2URI)
+            .sinceSeq(lastSeq)
+        )
+            .trigger();
+
+        assertTrue(result.isOk(), "The replication should complete ok");
+
+        List<ReplicationHistory> histories = result.getHistories();
+        assertThat(histories.size(), not(0));
+    }
 }
diff --git a/cloudant-client/src/test/java/com/cloudant/tests/ReplicatorTest.java b/cloudant-client/src/test/java/com/cloudant/tests/ReplicatorTest.java
index 182fe0c63..354fe97cd 100644
--- a/cloudant-client/src/test/java/com/cloudant/tests/ReplicatorTest.java
+++ b/cloudant-client/src/test/java/com/cloudant/tests/ReplicatorTest.java
@@ -1,5 +1,5 @@
 /*
- * Copyright © 2015, 2019 IBM Corp. All rights reserved.
+ * Copyright © 2015, 2021 IBM Corp. 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
@@ -131,4 +131,41 @@ public void replication_conflict() throws Exception {
         //a conflict
         assertConflictsNotZero(db2);
     }
+
+    @Test
+    public void replicator_since_seq() throws Exception {
+        String seq = db1.changes().getChanges().getResults().get(2).getSeq();
+        Response response = db1Resource.appendReplicatorAuth(account.replicator()
+            .replicatorDocId(repDocId)
+            .createTarget(true)
+            .source(db1URI)
+            .target(db2URI)
+            .sinceSeq(seq)
+        )
+            .save();
+
+        // find and remove replicator doc
+        String state = Utils.waitForReplicatorToComplete(account, response.getId());
+        assertTrue("completed".equalsIgnoreCase(state), "The replicator " +
+            "should reach completed state");
+    }
+
+    @Test
+    public void replicator_last_seq() throws Exception {
+        String lastSeq = db1Resource.get().changes().getChanges().getLastSeq();
+
+        Response response = db1Resource.appendReplicatorAuth(account.replicator()
+            .replicatorDocId(repDocId)
+            .createTarget(true)
+            .source(db1URI)
+            .target(db2URI)
+            .sinceSeq(lastSeq)
+        )
+            .save();
+
+        // find and remove replicator doc
+        String state = Utils.waitForReplicatorToComplete(account, response.getId());
+        assertTrue("completed".equalsIgnoreCase(state), "The replicator " +
+            "should reach completed state");
+    }
 }