diff --git a/Property/Converter/Configuration.ts b/Property/Converter/Configuration.ts
index d0d4990..e16357d 100644
--- a/Property/Converter/Configuration.ts
+++ b/Property/Converter/Configuration.ts
@@ -25,11 +25,9 @@ type GetValue<P extends string, Source extends Record<string, any>> = P extends
 type MaybePromise<T> = T | Promise<T> | Partial<number>
 export type Configuration<S extends Record<string, unknown> = Record<string, unknown>, T extends Payload = Payload> = {
 	[P in DotNotation<S>]?: {
-		encode: (
-			value: GetValue<P, S>
-		) => MaybePromise<(P extends DotNotation<T> ? GetValue<P, T> : Payload.Value) | undefined>
-		decode: (
-			value: (P extends DotNotation<T> ? GetValue<P, T> : Payload.Value) | undefined
+		encode?: (value: GetValue<P, S>) => MaybePromise<P extends DotNotation<T> ? GetValue<P, T> : Payload.Value>
+		decode?: (
+			value: P extends DotNotation<T> ? GetValue<P, T> : Payload.Value
 		) => MaybePromise<GetValue<P, S>> | undefined
 	}
 }
@@ -40,9 +38,9 @@ export namespace Configuration {
 		isly.record<Configuration>(
 			isly.string(),
 			isly
-				.object<{ encode: (...params: any[]) => any; decode: (...params: any[]) => any }>({
-					encode: isly.function(),
-					decode: isly.function(),
+				.object<{ encode?: (...params: any[]) => any; decode?: (...params: any[]) => any }>({
+					encode: isly.union(isly.function(), isly.undefined()),
+					decode: isly.union(isly.function(), isly.undefined()),
 				})
 				.optional()
 		)
diff --git a/Property/Converter/index.spec.ts b/Property/Converter/index.spec.ts
index 6aa36f1..2eeba2c 100644
--- a/Property/Converter/index.spec.ts
+++ b/Property/Converter/index.spec.ts
@@ -20,15 +20,15 @@ const target = {
 const conversionMap: authly.Property.Converter.Configuration<typeof source, typeof target> = {
 	foo: {
 		encode: value => value + "transformed",
-		decode: value => value?.replace("transformed", "") ?? "",
+		decode: value => value?.replace("transformed", ""),
 	},
 	num: {
 		encode: value => value + 5,
-		decode: value => (value ?? 0) - 5,
+		decode: value => value - 5,
 	},
 	array: {
 		encode: value => value.map(v => v / 5),
-		decode: value => value?.map(v => v * 5) ?? 0,
+		decode: value => value.map(v => v * 5),
 	},
 	"inside.foo": {
 		encode: () => "Valuedifferent",
@@ -40,7 +40,7 @@ const conversionMap: authly.Property.Converter.Configuration<typeof source, type
 	},
 	issued: {
 		encode: value => isoly.DateTime.epoch(value, "seconds"),
-		decode: value => isoly.DateTime.create(value ?? 0),
+		decode: value => isoly.DateTime.create(value),
 	},
 }
 
@@ -49,6 +49,9 @@ const converter = new authly.Property.Converter<typeof source, typeof target>(co
 describe("Converter", () => {
 	it("Converter.Configuration.is", async () => {
 		expect(authly.Property.Converter.Configuration.is(conversionMap)).toBe(true)
+		expect(authly.Property.Converter.Configuration.is({ foo: { encode: (value: string) => value } })).toEqual(true)
+		expect(authly.Property.Converter.Configuration.is({ foo: { decode: (value: string) => value } })).toEqual(true)
+		expect(authly.Property.Converter.Configuration.is({ foo: {} })).toEqual(true)
 	})
 	it("Empty Transformmap", async () => {
 		const converter = new authly.Property.Converter({})
@@ -76,4 +79,27 @@ describe("Converter", () => {
 		const converter = new authly.Property.Converter(map)
 		expect(await converter.apply({ flagly: "" })).toEqual({ flagly: {} })
 	})
+	it("Only encode", async () => {
+		const converter = new authly.Property.Converter<{ foo: number }, { foo: string }>({
+			foo: {
+				encode: value => value.toString(),
+			},
+		})
+		const source = { foo: 123 }
+		const target = await converter.apply(source)
+		expect(target).toEqual({ foo: "123" })
+		expect(await converter.reverse(target)).toEqual(target)
+	})
+	it("Only decode", async () => {
+		const converter = new authly.Property.Converter<{ foo: number }, { foo: string }>({
+			foo: {
+				decode: value => parseFloat(value),
+			},
+		})
+		const target = { foo: "123" }
+		const source = await converter.reverse(target)
+		expect(source).toEqual({ foo: 123 })
+		expect(target).toEqual({ foo: "123" })
+		expect(await converter.apply(source)).toEqual(source)
+	})
 })
diff --git a/Property/Converter/index.ts b/Property/Converter/index.ts
index 6d8efd7..b97204e 100644
--- a/Property/Converter/index.ts
+++ b/Property/Converter/index.ts
@@ -27,7 +27,7 @@ export class Converter<S extends Record<string, unknown> = Record<string, unknow
 		if (result[property[0]] != undefined)
 			result[property[0]] =
 				property.length == 1
-					? await mapping(result[property[0]] as Payload)
+					? (await mapping?.(result[property[0]] as Payload)) ?? result[property[0]]
 					: await this.convertProperty(result[property[0]] as Payload, property.slice(1), mapping)
 		return result
 	}