diff --git a/datatype/builtin/any.go b/datatype/builtin/any.go
index d96b26d..e1139b0 100644
--- a/datatype/builtin/any.go
+++ b/datatype/builtin/any.go
@@ -9,9 +9,9 @@ import (
 // AnyDataType is what its name tells
 type AnyDataType struct{}
 
-// Kind returns the kind of data
-func (AnyDataType) Kind() reflect.Kind {
-	return reflect.Interface
+// Type returns the type of data
+func (AnyDataType) Type() reflect.Type {
+	return reflect.TypeOf(interface{}(nil))
 }
 
 // Build returns the validator
diff --git a/datatype/builtin/bool.go b/datatype/builtin/bool.go
index 112158c..4d95547 100644
--- a/datatype/builtin/bool.go
+++ b/datatype/builtin/bool.go
@@ -9,9 +9,9 @@ import (
 // BoolDataType is what its name tells
 type BoolDataType struct{}
 
-// Kind returns the kind of data
-func (BoolDataType) Kind() reflect.Kind {
-	return reflect.Bool
+// Type returns the type of data
+func (BoolDataType) Type() reflect.Type {
+	return reflect.TypeOf(true)
 }
 
 // Build returns the validator
diff --git a/datatype/builtin/float.go b/datatype/builtin/float.go
index 3eb4c23..5016f10 100644
--- a/datatype/builtin/float.go
+++ b/datatype/builtin/float.go
@@ -10,9 +10,9 @@ import (
 // FloatDataType is what its name tells
 type FloatDataType struct{}
 
-// Kind returns the kind of data
-func (FloatDataType) Kind() reflect.Kind {
-	return reflect.Float64
+// Type returns the type of data
+func (FloatDataType) Type() reflect.Type {
+	return reflect.TypeOf(float64(0))
 }
 
 // Build returns the validator
diff --git a/datatype/builtin/int.go b/datatype/builtin/int.go
index 6559127..36b1038 100644
--- a/datatype/builtin/int.go
+++ b/datatype/builtin/int.go
@@ -11,9 +11,9 @@ import (
 // IntDataType is what its name tells
 type IntDataType struct{}
 
-// Kind returns the kind of data
-func (IntDataType) Kind() reflect.Kind {
-	return reflect.Int
+// Type returns the type of data
+func (IntDataType) Type() reflect.Type {
+	return reflect.TypeOf(int(0))
 }
 
 // Build returns the validator
diff --git a/datatype/builtin/string.go b/datatype/builtin/string.go
index b09b184..02be6ae 100644
--- a/datatype/builtin/string.go
+++ b/datatype/builtin/string.go
@@ -14,9 +14,9 @@ var variableLengthRegex = regexp.MustCompile(`^string\((\d+), ?(\d+)\)$`)
 // StringDataType is what its name tells
 type StringDataType struct{}
 
-// Kind returns the kind of data
-func (StringDataType) Kind() reflect.Kind {
-	return reflect.String
+// Type returns the type of data
+func (StringDataType) Type() reflect.Type {
+	return reflect.TypeOf(string(""))
 }
 
 // Build returns the validator.
diff --git a/datatype/builtin/uint.go b/datatype/builtin/uint.go
index d88fb5e..e59d2c1 100644
--- a/datatype/builtin/uint.go
+++ b/datatype/builtin/uint.go
@@ -11,9 +11,9 @@ import (
 // UintDataType is what its name tells
 type UintDataType struct{}
 
-// Kind returns the kind of data
-func (UintDataType) Kind() reflect.Kind {
-	return reflect.Uint
+// Type returns the type of data
+func (UintDataType) Type() reflect.Type {
+	return reflect.TypeOf(uint(0))
 }
 
 // Build returns the validator
diff --git a/datatype/types.go b/datatype/types.go
index a4761bb..c258b2f 100644
--- a/datatype/types.go
+++ b/datatype/types.go
@@ -10,6 +10,6 @@ type Validator func(value interface{}) (cast interface{}, valid bool)
 // definition does not match this T ; the registry is passed for recursive datatypes (e.g. slices, structs, etc)
 // to be able to access other datatypes
 type T interface {
-	Kind() reflect.Kind
+	Type() reflect.Type
 	Build(typeDefinition string, registry ...T) Validator
 }
diff --git a/internal/config/service.go b/internal/config/service.go
index d65251d..7c20724 100644
--- a/internal/config/service.go
+++ b/internal/config/service.go
@@ -238,7 +238,7 @@ func (svc *Service) validateInput(types []datatype.T) error {
 			param.Validator = dtype.Build(param.Type, types...)
 			if param.Validator != nil {
 				datatypeFound = true
-				param.Kind = dtype.Kind()
+				param.ExtractType = dtype.Type()
 				break
 			}
 		}
diff --git a/internal/config/types.go b/internal/config/types.go
index c3cc6f8..783959a 100644
--- a/internal/config/types.go
+++ b/internal/config/types.go
@@ -22,12 +22,12 @@ type Server struct {
 
 // Service represents a service definition (from api.json)
 type Service struct {
-	Method      string                `json:"method"`
-	Pattern     string                `json:"path"`
-	Scope       [][]string            `json:"scope"`
-	Description string                `json:"info"`
-	Input       map[string]*Parameter `json:"in"`
-	// Output      map[string]*Parameter `json:"out"`
+	Method      string                 `json:"method"`
+	Pattern     string                 `json:"path"`
+	Scope       [][]string             `json:"scope"`
+	Description string                 `json:"info"`
+	Input       map[string]*Parameter  `json:"in"`
+	Output      map[string]interface{} `json:"out"`
 
 	// references to url parameters
 	// format: '/uri/{param}'
@@ -46,8 +46,8 @@ type Parameter struct {
 	Description string `json:"info"`
 	Type        string `json:"type"`
 	Rename      string `json:"name,omitempty"`
-	// Kind of data the datatype returns
-	Kind reflect.Kind
+	// ExtractType is the type of data the datatype returns
+	ExtractType reflect.Type
 	// Optional is set to true when the type is prefixed with '?'
 	Optional bool