diff --git a/source/export/exporterobj.js b/source/export/exporterobj.js
index 252ee40..26c7031 100644
--- a/source/export/exporterobj.js
+++ b/source/export/exporterobj.js
@@ -37,6 +37,7 @@ OV.ExporterObj = class extends OV.ExporterBase
 		files.push (objFile);
 
 		let mtlWriter = new OV.TextWriter ();
+		mtlWriter.WriteLine (this.GetExportedByText ());
 		for (let materialIndex = 0; materialIndex < model.MaterialCount (); materialIndex++) {
 			let material = model.GetMaterial (materialIndex);
 			mtlWriter.WriteArrayLine (['newmtl', this.GetExportedMaterialName (material.name)]);
@@ -52,6 +53,7 @@ OV.ExporterObj = class extends OV.ExporterBase
 		mtlFile.SetContent (mtlWriter.GetText ());
 
 		let objWriter = new OV.TextWriter ();
+		objWriter.WriteLine (this.GetExportedByText ());
 		objWriter.WriteArrayLine (['mtllib', mtlFile.GetName ()]);
 		let vertexOffset = 0;
 		let normalOffset = 0;
@@ -105,4 +107,9 @@ OV.ExporterObj = class extends OV.ExporterBase
 
 		objFile.SetContent (objWriter.GetText ());        
 	}
+
+	GetExportedByText ()
+	{
+		return '# exported by https://3dviewer.net';
+	}	
 };
diff --git a/test/tests/exporter_test.js b/test/tests/exporter_test.js
index 1c7fd90..10b4241 100644
--- a/test/tests/exporter_test.js
+++ b/test/tests/exporter_test.js
@@ -74,6 +74,7 @@ describe ('Exporter', function () {
         assert.strictEqual (mtlFile.GetName (), 'model.mtl');
         assert.strictEqual (mtlFile.GetContent (),
         [
+            '# exported by https://3dviewer.net',
             'newmtl TestMaterial1',
             'Ka 0 0 0',
             'Kd 1 0 0',
@@ -95,6 +96,7 @@ describe ('Exporter', function () {
         assert.strictEqual (objFile.GetName (), 'model.obj');
         assert.strictEqual (objFile.GetContent (),
         [
+            '# exported by https://3dviewer.net',
             'mtllib model.mtl',
             'g TestMesh1',
             'v 0 0 1',