diff --git a/datamodel/low/reference.go b/datamodel/low/reference.go
index b0b2636..2ae2580 100644
--- a/datamodel/low/reference.go
+++ b/datamodel/low/reference.go
@@ -40,6 +40,10 @@ func (n NodeReference[T]) GenerateMapKey() string {
 	return fmt.Sprintf("%d:%d", n.ValueNode.Line, n.ValueNode.Column)
 }
 
+func (n NodeReference[T]) Mutate(value T) {
+	n.ValueNode.Value = fmt.Sprintf("%v", value)
+}
+
 func (n ValueReference[T]) IsEmpty() bool {
 	return n.ValueNode == nil
 }
@@ -56,6 +60,10 @@ func (n KeyReference[T]) GenerateMapKey() string {
 	return fmt.Sprintf("%d:%d", n.KeyNode.Line, n.KeyNode.Column)
 }
 
+func (n ValueReference[T]) Mutate(value T) {
+	n.ValueNode.Value = fmt.Sprintf("%v", value)
+}
+
 func IsCircular(node *yaml.Node, idx *index.SpecIndex) bool {
 	if idx == nil {
 		return false // no index! nothing we can do.
diff --git a/datamodel/spec_info.go b/datamodel/spec_info.go
index ed0d141..6f1a536 100644
--- a/datamodel/spec_info.go
+++ b/datamodel/spec_info.go
@@ -13,6 +13,11 @@ import (
 	"time"
 )
 
+const (
+	JSONFileType = "json"
+	YAMLFileType = "yaml"
+)
+
 // SpecInfo represents a 'ready-to-process' OpenAPI Document.
 type SpecInfo struct {
 	SpecType           string                  `json:"type"`
@@ -59,9 +64,9 @@ func ExtractSpecInfo(spec []byte) (*SpecInfo, error) {
 	}
 
 	if runes[0] == '{' && runes[len(runes)-1] == '}' {
-		specVersion.SpecFileType = "json"
+		specVersion.SpecFileType = JSONFileType
 	} else {
-		specVersion.SpecFileType = "yaml"
+		specVersion.SpecFileType = YAMLFileType
 	}
 
 	err := yaml.Unmarshal(spec, &parsedSpec)
diff --git a/document.go b/document.go
index 2084df6..28f297d 100644
--- a/document.go
+++ b/document.go
@@ -10,6 +10,8 @@ import (
 	v3high "github.com/pb33f/libopenapi/datamodel/high/3.0"
 	v2low "github.com/pb33f/libopenapi/datamodel/low/2.0"
 	v3low "github.com/pb33f/libopenapi/datamodel/low/3.0"
+	"github.com/pb33f/libopenapi/utils"
+	"gopkg.in/yaml.v3"
 )
 
 type Document struct {
@@ -40,6 +42,18 @@ func (d *Document) GetSpecInfo() *datamodel.SpecInfo {
 	return d.info
 }
 
+func (d *Document) Serialize() ([]byte, error) {
+	if d.info == nil {
+		return nil, fmt.Errorf("unable to serialize, document has not yet been initialized")
+	}
+	if d.info.SpecFileType == datamodel.YAMLFileType {
+		return yaml.Marshal(d.info.RootNode)
+	} else {
+		yamlData, _ := yaml.Marshal(d.info.RootNode)
+		return utils.ConvertYAMLtoJSON(yamlData)
+	}
+}
+
 func (d *Document) BuildV2Document() (*DocumentModel[v2high.Swagger], []error) {
 	var errors []error
 	if d.info == nil {
diff --git a/document_test.go b/document_test.go
index 6643d88..f4c8101 100644
--- a/document_test.go
+++ b/document_test.go
@@ -106,3 +106,63 @@ paths:
 	assert.Len(t, docErr, 1)
 	assert.Nil(t, v3Doc)
 }
+
+func TestDocument_Serialize_Error(t *testing.T) {
+	doc := new(Document) // not how this should be instantiated.
+	_, err := doc.Serialize()
+	assert.Error(t, err)
+}
+
+func TestDocument_Serialize(t *testing.T) {
+
+	yml := `openapi: 3.0
+info:
+    title: The magic API
+`
+	doc, _ := NewDocument([]byte(yml))
+	serial, err := doc.Serialize()
+	assert.NoError(t, err)
+	assert.Equal(t, yml, string(serial))
+}
+
+func TestDocument_Serialize_Modified(t *testing.T) {
+
+	yml := `openapi: 3.0
+info:
+    title: The magic API
+`
+
+	ymlModified := `openapi: 3.0
+info:
+    title: The magic API - but now, altered!
+`
+	doc, _ := NewDocument([]byte(yml))
+
+	v3Doc, _ := doc.BuildV3Document()
+
+	v3Doc.Model.Info.GoLow().Title.Mutate("The magic API - but now, altered!")
+
+	serial, err := doc.Serialize()
+	assert.NoError(t, err)
+	assert.Equal(t, ymlModified, string(serial))
+}
+
+func TestDocument_Serialize_JSON_Modified(t *testing.T) {
+
+	json := `{ 'openapi': '3.0',
+ 'info': {
+   'title': 'The magic API'
+ }
+}
+`
+	jsonModified := `{"info":{"title":"The magic API - but now, altered!"},"openapi":"3.0"}`
+	doc, _ := NewDocument([]byte(json))
+
+	v3Doc, _ := doc.BuildV3Document()
+
+	v3Doc.Model.Info.GoLow().Title.Mutate("The magic API - but now, altered!")
+
+	serial, err := doc.Serialize()
+	assert.NoError(t, err)
+	assert.Equal(t, jsonModified, string(serial))
+}
diff --git a/libopenapi.go b/libopenapi.go
index 1bb36d8..320b093 100644
--- a/libopenapi.go
+++ b/libopenapi.go
@@ -1,51 +1,41 @@
 package main
 
-import (
-	"fmt"
-	"github.com/pb33f/libopenapi/datamodel"
-	high "github.com/pb33f/libopenapi/datamodel/high/3.0"
-	low "github.com/pb33f/libopenapi/datamodel/low/3.0"
-	"gopkg.in/yaml.v3"
-	"io/ioutil"
-	"os"
-)
-
-func main() {
-
-	testData := `openapi: 3.0.1
-info:
-  title: this is a title
-  description: this is a description
-tags:
-  - name: Tag A
-    description: cake
-    x-hack: true
-  - name: Tag B
-    description: coffee
-    x-code: hack`
-
-	data := []byte(testData)
-	_ = ioutil.WriteFile("sample.yaml", data, 0664)
-
-	info, _ := datamodel.ExtractSpecInfo(data)
-	lowDoc, err := low.CreateDocument(info)
-	if len(err) > 0 {
-		for e := range err {
-			fmt.Printf("%e\n", err[e])
-		}
-		return
-	}
-	highDoc := high.NewDocument(lowDoc)
-
-	highDoc.Info.GoLow().Title.ValueNode.Value = "let's hack this"
-	//highDoc.Tags[0].SetName("We are a new name now")
-	//highDoc.Tags[0].SetDescription("and a new description")
-
-	//newTag := lowDoc.AddTag()
-	//fmt.Println(newTag)
-	modified, _ := yaml.Marshal(info.RootNode)
-	fmt.Println(string(modified))
-
-	os.Remove("sample.yaml")
-
-}
+//func main() {
+//
+//	testData := `openapi: 3.0.1
+//info:
+//  title: this is a title
+//  description: this is a description
+//tags:
+//  - name: Tag A
+//    description: cake
+//    x-hack: true
+//  - name: Tag B
+//    description: coffee
+//    x-code: hack`
+//
+//	data := []byte(testData)
+//	_ = ioutil.WriteFile("sample.yaml", data, 0664)
+//
+//	info, _ := datamodel.ExtractSpecInfo(data)
+//	lowDoc, err := low.CreateDocument(info)
+//	if len(err) > 0 {
+//		for e := range err {
+//			fmt.Printf("%e\n", err[e])
+//		}
+//		return
+//	}
+//	highDoc := high.NewDocument(lowDoc)
+//
+//	highDoc.Info.GoLow().Title.ValueNode.Value = "let's hack this"
+//	//highDoc.Tags[0].SetName("We are a new name now")
+//	//highDoc.Tags[0].SetDescription("and a new description")
+//
+//	//newTag := lowDoc.AddTag()
+//	//fmt.Println(newTag)
+//	modified, _ := yaml.Marshal(info.RootNode)
+//	fmt.Println(string(modified))
+//
+//	os.Remove("sample.yaml")
+//
+//}