diff --git a/NineChronicles.Headless/GraphTypes/StandaloneSubscription.cs b/NineChronicles.Headless/GraphTypes/StandaloneSubscription.cs
index fb5738403..8b249aebc 100644
--- a/NineChronicles.Headless/GraphTypes/StandaloneSubscription.cs
+++ b/NineChronicles.Headless/GraphTypes/StandaloneSubscription.cs
@@ -15,6 +15,7 @@
 using System.Reactive.Linq;
 using System.Reactive.Subjects;
 using System.Reactive.Disposables;
+using System.Text.RegularExpressions;
 using Bencodex.Types;
 using Libplanet.Crypto;
 using Libplanet.Types.Assets;
@@ -145,7 +146,7 @@ public StandaloneSubscription(StandaloneContext standaloneContext)
                 Arguments = new QueryArguments(
                     new QueryArgument<NonNullGraphType<StringGraphType>>
                     {
-                        Description = "A type of action in transaction.",
+                        Description = "A regular expression to filter transactions based on action type.",
                         Name = "actionType",
                     }
                 ),
@@ -304,7 +305,7 @@ private IObservable<Tx> SubscribeTx(IResolveFieldContext context)
                         return false;
                     }
 
-                    return typeId == actionType;
+                    return Regex.IsMatch(typeId, actionType);
                 }))
                 .Select(transaction => new Tx
                 {
diff --git a/NineChronicles.Headless/GraphTypes/TransactionType.cs b/NineChronicles.Headless/GraphTypes/TransactionType.cs
index 3a539f735..d56d4391a 100644
--- a/NineChronicles.Headless/GraphTypes/TransactionType.cs
+++ b/NineChronicles.Headless/GraphTypes/TransactionType.cs
@@ -1,3 +1,4 @@
+using System;
 using GraphQL.Types;
 using Libplanet.Explorer.GraphTypes;
 using Libplanet.Types.Tx;
@@ -48,6 +49,15 @@ public TransactionType()
                 description: "A list of actions in this transaction.",
                 resolve: context => context.Source.Actions
             );
+
+            Field<NonNullGraphType<StringGraphType>>(
+                name: "SerializedPayload",
+                description: "A serialized tx payload in base64 string.",
+                resolve: x =>
+                {
+                    byte[] bytes = x.Source.Serialize();
+                    return Convert.ToBase64String(bytes);
+                });
         }
     }
 }