diff --git a/repository/Grease-Core.package/GRPlatform.class/instance/base64Encode..st b/repository/Grease-Core.package/GRPlatform.class/instance/base64Encode..st
new file mode 100644
index 00000000..1e94d60c
--- /dev/null
+++ b/repository/Grease-Core.package/GRPlatform.class/instance/base64Encode..st
@@ -0,0 +1,4 @@
+encoding
+base64Encode: aByteArray
+	"Base64 encode the given byte array and answer the result as a String."
+	self subclassResponsibility
\ No newline at end of file
diff --git a/repository/Grease-GemStone-Core.package/GRGemStonePlatform.class/instance/base64Encode..st b/repository/Grease-GemStone-Core.package/GRGemStonePlatform.class/instance/base64Encode..st
new file mode 100644
index 00000000..4a3631f8
--- /dev/null
+++ b/repository/Grease-GemStone-Core.package/GRGemStonePlatform.class/instance/base64Encode..st
@@ -0,0 +1,3 @@
+encoding
+base64Encode: aByteArray
+	^ (Base64MimeConverter mimeEncode: aByteArray readStream) contents
diff --git a/repository/Grease-Pharo100-Core.package/GRPharoPlatform.class/instance/base64Encode..st b/repository/Grease-Pharo100-Core.package/GRPharoPlatform.class/instance/base64Encode..st
new file mode 100644
index 00000000..4cb93d20
--- /dev/null
+++ b/repository/Grease-Pharo100-Core.package/GRPharoPlatform.class/instance/base64Encode..st
@@ -0,0 +1,3 @@
+encoding
+base64Encode: aByteArray
+	^ aByteArray base64Encoded
\ No newline at end of file
diff --git a/repository/Grease-Pharo60-Core.package/GRPharoPlatform.class/instance/base64Encode..st b/repository/Grease-Pharo60-Core.package/GRPharoPlatform.class/instance/base64Encode..st
new file mode 100644
index 00000000..f5e24f05
--- /dev/null
+++ b/repository/Grease-Pharo60-Core.package/GRPharoPlatform.class/instance/base64Encode..st
@@ -0,0 +1,3 @@
+encoding
+base64Encode: aByteArray
+	^ (Base64MimeConverter base64Encode: aByteArray readStream) contents
diff --git a/repository/Grease-Pharo70-Core.package/GRPharoPlatform.class/instance/base64Encode..st b/repository/Grease-Pharo70-Core.package/GRPharoPlatform.class/instance/base64Encode..st
new file mode 100644
index 00000000..4cb93d20
--- /dev/null
+++ b/repository/Grease-Pharo70-Core.package/GRPharoPlatform.class/instance/base64Encode..st
@@ -0,0 +1,3 @@
+encoding
+base64Encode: aByteArray
+	^ aByteArray base64Encoded
\ No newline at end of file
diff --git a/repository/Grease-Pharo90-Core.package/GRPharoPlatform.class/instance/base64Encode..st b/repository/Grease-Pharo90-Core.package/GRPharoPlatform.class/instance/base64Encode..st
new file mode 100644
index 00000000..4cb93d20
--- /dev/null
+++ b/repository/Grease-Pharo90-Core.package/GRPharoPlatform.class/instance/base64Encode..st
@@ -0,0 +1,3 @@
+encoding
+base64Encode: aByteArray
+	^ aByteArray base64Encoded
\ No newline at end of file
diff --git a/repository/Grease-Squeak5-Core.package/GRPharoPlatform.class/instance/base64Encode..st b/repository/Grease-Squeak5-Core.package/GRPharoPlatform.class/instance/base64Encode..st
new file mode 100644
index 00000000..4cb93d20
--- /dev/null
+++ b/repository/Grease-Squeak5-Core.package/GRPharoPlatform.class/instance/base64Encode..st
@@ -0,0 +1,3 @@
+encoding
+base64Encode: aByteArray
+	^ aByteArray base64Encoded
\ No newline at end of file
diff --git a/repository/Grease-Squeak6-Core.package/GRPharoPlatform.class/instance/base64Encode..st b/repository/Grease-Squeak6-Core.package/GRPharoPlatform.class/instance/base64Encode..st
new file mode 100644
index 00000000..4cb93d20
--- /dev/null
+++ b/repository/Grease-Squeak6-Core.package/GRPharoPlatform.class/instance/base64Encode..st
@@ -0,0 +1,3 @@
+encoding
+base64Encode: aByteArray
+	^ aByteArray base64Encoded
\ No newline at end of file
diff --git a/repository/Grease-Tests-Core.package/GRPlatformTest.class/instance/testBase64Encode.st b/repository/Grease-Tests-Core.package/GRPlatformTest.class/instance/testBase64Encode.st
new file mode 100644
index 00000000..d1a2b4be
--- /dev/null
+++ b/repository/Grease-Tests-Core.package/GRPlatformTest.class/instance/testBase64Encode.st
@@ -0,0 +1,14 @@
+tests
+testBase64Encode
+	| input |
+	input := #(
+		(97 110 121 32 99 97 114 110 97 108 32 112 108 101 97 115 117 114 101 46) 'YW55IGNhcm5hbCBwbGVhc3VyZS4=' 
+		(97 110 121 32 99 97 114 110 97 108 32 112 108 101 97 115 117 114 101) 'YW55IGNhcm5hbCBwbGVhc3VyZQ=='
+		(97 110 121 32 99 97 114 110 97 108 32 112 108 101 97 115 117 114) 'YW55IGNhcm5hbCBwbGVhc3Vy'
+		(97 110 121 32 99 97 114 110 97 108 32 112 108 101 97 115 117) 'YW55IGNhcm5hbCBwbGVhc3U=' 
+		(97 110 121 32 99 97 114 110 97 108 32 112 108 101 97 115) 'YW55IGNhcm5hbCBwbGVhcw==').
+	1 to: input size by: 2 do: [ :index |
+		| decoded expected |
+		decoded := GRPlatform current base64Encode: (input at: index) asByteArray.
+		expected := input at: index + 1.
+		self assert: decoded = expected ]
\ No newline at end of file