diff --git a/swh/graphql/app.py b/swh/graphql/app.py
--- a/swh/graphql/app.py
+++ b/swh/graphql/app.py
@@ -33,8 +33,8 @@
     resolvers.branch_target,
     resolvers.release_target,
     resolvers.directory_entry_target,
+    resolvers.binary_string,
     scalars.id_scalar,
-    scalars.string_scalar,
     scalars.datetime_scalar,
     scalars.swhid_scalar,
 )
diff --git a/swh/graphql/resolvers/resolvers.py b/swh/graphql/resolvers/resolvers.py
--- a/swh/graphql/resolvers/resolvers.py
+++ b/swh/graphql/resolvers/resolvers.py
@@ -15,6 +15,7 @@
 from graphql.type import GraphQLResolveInfo
 
 from swh.graphql import resolvers as rs
+from swh.graphql.utils import utils
 
 from .resolver_factory import get_connection_resolver, get_node_resolver
 
@@ -28,6 +29,7 @@
 release: ObjectType = ObjectType("Release")
 directory: ObjectType = ObjectType("Directory")
 directory_entry: ObjectType = ObjectType("DirectoryEntry")
+binary_string: ObjectType = ObjectType("BinaryString")
 
 branch_target: UnionType = UnionType("BranchTarget")
 release_target: UnionType = UnionType("ReleaseTarget")
@@ -243,3 +245,13 @@
     Generic resolver for all the union types
     """
     return obj.is_type_of()
+
+
+@binary_string.field("text")
+def binary_string_text_resolver(obj, *args, **kw):
+    return obj.decode(utils.ENCODING, "replace")
+
+
+@binary_string.field("base64")
+def binary_string_base64_resolver(obj, *args, **kw):
+    return utils.get_b64_string(obj)
diff --git a/swh/graphql/resolvers/scalars.py b/swh/graphql/resolvers/scalars.py
--- a/swh/graphql/resolvers/scalars.py
+++ b/swh/graphql/resolvers/scalars.py
@@ -14,7 +14,6 @@
 datetime_scalar = ScalarType("DateTime")
 swhid_scalar = ScalarType("SWHID")
 id_scalar = ScalarType("ID")
-string_scalar = ScalarType("String")
 
 
 @id_scalar.serializer
@@ -24,13 +23,6 @@
     return value
 
 
-@string_scalar.serializer
-def serialize_string(value):
-    if type(value) is bytes:
-        return value.decode("utf-8")
-    return value
-
-
 @datetime_scalar.serializer
 def serialize_datetime(value):
     # FIXME, handle error and return None
diff --git a/swh/graphql/resolvers/visit.py b/swh/graphql/resolvers/visit.py
--- a/swh/graphql/resolvers/visit.py
+++ b/swh/graphql/resolvers/visit.py
@@ -14,7 +14,7 @@
     @property
     def id(self):
         # FIXME, use a better id
-        return utils.b64encode(f"{self.origin}-{str(self.visit)}")
+        return utils.get_b64_string(f"{self.origin}-{str(self.visit)}")
 
     @property
     def visitId(self):  # To support the schema naming convention
diff --git a/swh/graphql/schema/schema.graphql b/swh/graphql/schema/schema.graphql
--- a/swh/graphql/schema/schema.graphql
+++ b/swh/graphql/schema/schema.graphql
@@ -44,6 +44,22 @@
   hasNextPage: Boolean!
 }
 
+"""
+Binary strings; different encodings
+"""
+type BinaryString {
+  """
+  Utf-8 encoded value, any non Unicode character will be replaced
+  """
+  text: String
+
+  """
+  base64 encoded value
+  """
+  base64: String
+}
+
+
 """
 Connection to origins
 """
@@ -411,17 +427,17 @@
   """
   User's email address
   """
-  email: String
+  email: BinaryString
 
   """
   User's name
   """
-  name: String
+  name: BinaryString
 
   """
   User's full name
   """
-  fullname: String
+  fullname: BinaryString
 }
 
 """
@@ -448,7 +464,7 @@
   """
   Branch name
   """
-  name: String
+  name: BinaryString
 
   """
   Type of Branch target
@@ -518,7 +534,7 @@
   """
   Message associated to the revision
   """
-  message: String
+  message: BinaryString
 
   """
   """
@@ -607,12 +623,12 @@
   """
   The name of the release
   """
-  name: String
+  name: BinaryString
 
   """
   The message associated to the release
   """
-  message: String
+  message: BinaryString
 
   """
   """
@@ -695,7 +711,7 @@
   """
   The directory entry name
   """
-  name: String
+  name: BinaryString
 
   """
   Directory entry object type; can be file, dir or rev
diff --git a/swh/graphql/tests/unit/resolvers/test_resolvers.py b/swh/graphql/tests/unit/resolvers/test_resolvers.py
--- a/swh/graphql/tests/unit/resolvers/test_resolvers.py
+++ b/swh/graphql/tests/unit/resolvers/test_resolvers.py
@@ -118,3 +118,11 @@
         obj = mocker.Mock()
         obj.is_type_of.return_value = "test"
         assert rs.union_resolver(obj) == "test"
+
+    def test_binary_string_text_resolver(self):
+        text = rs.binary_string_text_resolver(b"test", None)
+        assert text == "test"
+
+    def test_binary_string_base64_resolver(self):
+        b64string = rs.binary_string_base64_resolver(b"test", None)
+        assert b64string == "dGVzdA=="
diff --git a/swh/graphql/tests/unit/utils/test_utils.py b/swh/graphql/tests/unit/utils/test_utils.py
--- a/swh/graphql/tests/unit/utils/test_utils.py
+++ b/swh/graphql/tests/unit/utils/test_utils.py
@@ -9,8 +9,11 @@
 
 
 class TestUtils:
-    def test_b64encode(self):
-        assert utils.b64encode("testing") == "dGVzdGluZw=="
+    def test_get_b64_string(self):
+        assert utils.get_b64_string("testing") == "dGVzdGluZw=="
+
+    def test_get_b64_string_binary(self):
+        assert utils.get_b64_string(b"testing") == "dGVzdGluZw=="
 
     def test_get_encoded_cursor_is_none(self):
         assert utils.get_encoded_cursor(None) is None
diff --git a/swh/graphql/utils/utils.py b/swh/graphql/utils/utils.py
--- a/swh/graphql/utils/utils.py
+++ b/swh/graphql/utils/utils.py
@@ -9,21 +9,25 @@
 
 from swh.storage.interface import PagedResult
 
+ENCODING = "utf-8"
 
-def b64encode(text: str) -> str:
-    return base64.b64encode(bytes(text, "utf-8")).decode("utf-8")
+
+def get_b64_string(source) -> str:
+    if type(source) is str:
+        source = source.encode(ENCODING)
+    return base64.b64encode(source).decode("ascii")
 
 
 def get_encoded_cursor(cursor: str) -> str:
     if cursor is None:
         return None
-    return b64encode(cursor)
+    return get_b64_string(cursor)
 
 
 def get_decoded_cursor(cursor: str) -> str:
     if cursor is None:
         return None
-    return base64.b64decode(cursor).decode("utf-8")
+    return base64.b64decode(cursor).decode(ENCODING)
 
 
 def str_to_sha1(sha1: str) -> bytearray: