Customize JSON Responses

The JSON Responses for all ServiceStack Services can be configured Globally, individually per-Service or customized per-request by the client using the ?jsconfig QueryString modifier.

Global Default JSON Configuration

ServiceStack uses the ServiceStack.Text Serializers for its built-in JSON/JSV and CSV serialization. The serialization can be customized globally by configuring the JsConfig or type-specific JsConfig<T> static classes with your preferred defaults, e.g:

public override void Configure(Container container)
    JsConfig.Init(new ServiceStack.Text.Config {
        TextCase = TextCase.SnakeCase,
        ExcludeDefaultValues = true,

    JsConfig<Guid>.SerializeFn = guid => guid.ToString("D");
    JsConfig<TimeSpan>.SerializeFn = time => 
        (time.Ticks < 0 ? "-" : "") + time.ToString("hh':'mm':'ss'.'fffffff");

Customize JSON Responses in Service

The Global Defaults can be overridden on a adhoc basis by returning your Response DTO in a custom HttpResult configured with a custom JS Config Scope, e.g:

return new HttpResult(responseDto) {
    ResultScope = () => 
        JsConfig.With(new Config { IncludeNullValues = true, ExcludeDefaultValues = true })

This has the same behavior for your Service Responses as creating a Custom Config Scope for adhoc Serialization that overrides Global Configuration, e.g:

using (JsConfig.With(new Config { IncludeNullValues = true, ExcludeDefaultValues = true }))
    var json = dto.ToJson();

Customize JSON Responses from Client

The JSON and JSV Responses for all Services (inc. Auto Query Services) can also be further customized with the new ?jsconfig QueryString param which lets your Service consumers customize the returned JSON Response to their preference. This works similar to having wrapped your Service response in a HttpResult with a Custom ResultScope in the Service implementation to enable non-default customization of a Services response, e.g:


Works similarly to:

return new HttpResult(new { TheKey = "value", Foo=0 }) {
    ResultScope = () => 
        JsConfig.With(new Config { TextCase = TextCase.SnakeCase, ExcludeDefaultValues = true })

Which results in lowercase_underscore key names with any properties with default values removed:


It also supports cascading server and client ResultScopes, with the client ?jsconfig taking precedence.

Nearly all JsConfig scope options are supported other than delegates and complex type configuration properties.

Camel Humps Notation

JsConfig also supports Camel Humps notation letting you target a configuration by just using the Uppercase Letters in the property name which is also case-insensitive so an equivalent shorter version of the above config can be:


Camel Humps also works with Enum Values so both these two configurations are the same:


Custom JSON Live Example

AutoQuery Viewer makes use of this feature in order to return human readable dates using the new ISO8601DateOnly DateHandler Enum Value as well as appending ExcludeDefaultValues when specifying custom fields so that any unpopulated value type properties with default values are excluded from the JSON Response.

Custom JSON Settings

The presence of a bool configuration property will be set to true unless they have a false or 0 value in which case they will be set to false, e.g:


For a quick reference the following bool customizations are supported:


DateHandler (dh)


TimeSpanHandler (tsh)


PropertyConvention (pc)


Create Custom Scopes using String config

You can also create a scope from a string manually using JsConfig.CreateScope(), e.g:

using (JsConfig.CreateScope("EmitLowercaseUnderscoreNames,ExcludeDefaultValues,dh:ut")) 
    var json = dto.ToJson();

If you don't wish for consumers to be able to customize JSON responses this feature can be disabled with Config.AllowJsConfig=false.

Accept arbitrary JavaScript or JSON Objects

Whilst we recommend creating well-defined, Typed Service Contracts for your Services, there are rare situations where you'd want to be able to accept an arbitrary JSON payload, an example of this is with integration hooks with a 3rd party provider that calls back into your Service with a custom JSON payload, e.g:

public class Callback : IReturn<CallbackResponse>
    public object Payload { get; set; }

ServiceStack object properties are now deserialized using #Script JS Utils which can parse any JavaScript or JSON data structure. So if a POST callback was sent to the above service containing:

POST /callback

{"payload": {"id":1,"name":"foo", "List": [{"id":2,"name":"bar"}], "Dictionary": {"key":{"id":3,"name":"bax"}‎} }‎}

It will parsed into the appropriate .NET Types and generic collections which can be accessed with:

public object Any(Callback request)
    var payload = request.Object as Dictionary<string,object>;
    var id = payload["id"];                             //= 1
    var name = payload["name"];                         //= foo
    var list = payload["List"] as List<object>;
    var firstListItem = list[0] as Dictionary<string, object>;
    var firstListName = firstListItem["name"];          //= bar
    var dictionary = payload["Dictionary"] as Dictionary<string, object>;
    var dictionaryValue = dictionary["Key"] as Dictionary<string, object>;
    var dictionaryValueName = dictionaryValue["name"];  //= baz

As it's using JS Utils it can also accept JavaScript object literal syntax, e.g: { payload: { id: 1 } }.

Avoid unknown Types in ServiceContracts

Whilst this feature enables some flexibility by effectively poking a hole in your Service Contract as a placeholder for any arbitrary JS data structure, we still recommend only using object properties sparingly when it's needed as it only works with JSON/JSV Services, is subject to security restrictions, can't be documented in Metadata Services and isn't supported in most Add ServiceStack Reference languages.