The @servicestack/client library enables the best end-to-end typed developer experience for calling ServiceStack APIs in any TypeScript or JavaScript project.

Usage in TypeScript or npm projects

Projects using TypeScript or any npm build system can install the dependency-free library with:

npm install @servicestack/client

Which can be used with your APIs typed DTOs that TypeScript projects can generate using TypeScript Add ServiceStack Reference with:

x ts https://localhost:5001

Which will save your API DTOs to dtos.ts that can be referenced in your code with:

import { Hello } from "./dtos"

JavaScript npm projects

Non-TypeScript npm projects can choose to either have TypeScript generate the DTOs into the preferred JavaScript target:

tsc dtos.ts

Alternatively they can generate ES6 annotated DTOs using JavaScript Add ServiceStack Reference with:

x mjs https://localhost:5001

Which will save your API DTOs to dtos.mjs where they can be referenced in your code with:

import { Hello } from "./dtos.mjs"

Example Usage

Either solution gives you the same productive end-to-end Typed API access, e.g:

import { JsonServiceClient } from "@servicestack/client"

const client = new JsonServiceClient()

const api = await client.api(new Hello({ Name: 'World' }))
if (api.succeeded) {
} else {

Usage in .NET Apps without npm

Modern JavaScript Apps not using an npm build system like the Razor Vue Tailwind templates can download @servicestack/client from:

Then use an importmap to specify where to load @servicestack/client from, e.g:

<script async src="https://ga.jspm.io/npm:es-module-shims@1.6.3/dist/es-module-shims.js"></script><!--safari-->
<script type="importmap">
    "imports": {
        "@servicestack/client": "/js/servicestack-client.mjs"

ImportMap in Razor Pages or MVC

Razor Pages or MVC projects can use @Html.ImportMap() in _Layout.cshtml to use different builds for development and production, e.g:

@if (Context.Request.Headers.UserAgent.Any(x => x.Contains("Safari") && !x.Contains("Chrome")))
    <script async src="https://ga.jspm.io/npm:es-module-shims@1.6.3/dist/es-module-shims.js"></script>
    ["@servicestack/client"] = ("/js/servicestack-client.mjs", "/js/servicestack-client.min.mjs"),

This lets your source code reference the library by package name to enable using the same source code in a JavaScript Module, e.g:

<script type="module">
import { JsonServiceClient } from "@servicestack/client"

const client = new JsonServiceClient()

const api = await client.api(new Hello({ Name: 'World' }))

JavaScript API DTOs

Your JavaScript API DTOs can either directly reference the /types/mjs endpoint:

import { Hello } from '/types/mjs'

Enable static analysis and intelli-sense

Or for better IDE intelli-sense during development, save the annotated Typed DTOs to disk with the x dotnet tool:

x mjs

Then reference it instead to enable IDE static analysis when calling Typed APIs from JavaScript:

import { Hello } from '/js/dtos.mjs'
client.api(new Hello({ name }))

To also enable static analysis for @servicestack/client, install the dependency-free library as a dev dependency:

npm install -D @servicestack/client

Where only its TypeScript definitions are used by the IDE during development to enable its type-checking and intelli-sense.

Support Legacy Browsers

JavaScript Projects needing to support legacy browsers can use ES3 Common.js DTOs to enable access using old-style <script> includes.


To create JsonServiceClient instances in v6+ projects using the JSON /api route use:

const client = new JsonServiceClient(baseUrl)

Where it's configured to not use any JSON HTTP Headers to enable more efficient CORS requests without preflight requests.

Alternatively if needed you can use useBasePath() to revert back to using legacy /json/reply pre-defined Routes:

const client = new JsonServiceClient(baseUrl).useBasePath()

API Reference

API method

The api returns a typed ApiResult<Response> Value Result that encapsulates either a Typed Response or a structured API Error populated in ResponseStatus allowing you to handle API responses programmatically without try/catch handling:

const api = client.api(new Hello({ name }))
if (api.failed) {
    console.log(`Greeting failed! ${e.errorCode}: ${e.errorMessage}`);

console.log(`API Says: ${api.response.result}`) //api.succeeded

Simplified API Handling

Being able to treat errors as values greatly increases the ability to programmatically handle and genericise api handling and greatly simplifies functionality needing to handle both successful and error responses like binding to UI components.

An example of this is below where we're able to concurrently fire off multiple unrelated async requests in parallel, wait for them all to complete, print out the ones that have succeeded or failed then access their strong typed responses:

import { JsonServiceClient } from "@servicestack/client"

let requests:ApiRequest[] = [
    new AppOverview(),            // GET => AppOverviewResponse
    new DeleteTechnology(),       // DELETE => IReturnVoid (requires auth) 
    new GetAllTechnologies(),     // GET => GetAllTechnologiesResponse
    new GetAllTechnologyStacks(), // GET => GetAllTechnologyStacksResponse

let results = await Promise.all(requests.map(async (request) =>
    ({ request, api:await client.api(request) as ApiResponse}) ))

let failed = results.filter(x => x.api.failed)
console.log(`${failed.length} failed:`)
failed.forEach(x =>
    console.log(`    ${x.request.getTypeName()} Request Failed: ${failed.map(x => x.api.errorMessage)}`))

let succeeded = results.filter(x => x.api.succeeded)
console.log(`\n${succeeded.length} succeeded: ${succeeded.map(x => x.request.getTypeName()).join(', ')}`)

let r = succeeded.find(x => x.request.getTypeName() == 'AppOverview')?.api.response as AppOverviewResponse
if (r) console.log(`Top 5 Technologies: ${r.topTechnologies.slice(0,4).map(tech => tech.name).join(', ')}`)


1 failed
DeleteTechnology Request Failed: Unauthorized

3 succeeded: AppOverview, GetAllTechnologies, GetAllTechnologyStacks
Top 5 Technologies: Redis, MySQL, Amazon EC2, Nginx

Being able to treat Errors as values has dramatically reduced the effort required to accomplish the same feat if needing to handle errors with try/catch.

Ideal Typed Message-based API

The TypeScript JsonServiceClient enables the same productive, typed API development experience available in ServiceStack's other 1st-class supported client platforms.

The JsonServiceClient leverages the additional type hints ServiceStack embeds in each TypeScript Request DTO to achieve the ideal typed, message-based API - so all API requests benefit from a succinct, boilerplate-free Typed API.

Here's a quick look at what it looks like. The example below shows how to create a C# Gist in Gistlyn after adding a TypeScript ServiceStack Reference to gistlyn.com and installing the @servicestack/client npm package:

import { JsonServiceClient } from '@servicestack/client';
import { StoreGist, GithubFile } from './dtos';

const client = new JsonServiceClient("https://gistlyn.com");

const request = new StoreGist({
    files: { 
        [file.filename]: new GithubFile({
            filename: 'main.cs',
            content: 'var greeting = "Hi, from TypeScript!";' 

const api = client.api(request); //response:StoreGistResponse
if (api.succeeded) {
    console.log(`New C# Gist was created with id: ${r.gist}`);
    location.href = `https://gist.cafe/${r.gist}`;
} else {
    console.log("Failed to create Gist: ", e.errorMessage);

Where the response param is typed to StoreGistResponse DTO Type.

Sending additional arguments with Typed API Requests

Many AutoQuery Services utilize implicit conventions to query fields that aren't explicitly defined on AutoQuery Request DTOs, these can now be queried by specifying additional arguments with the typed Request DTO, e.g:

//typed to QueryResponse<TechnologyStack> 
const response = await client.get(new FindTechStacks(), { VendorName: "ServiceStack" });

Which will return TechStacks developed by ServiceStack.

Calling APIs with Custom URLs

You can call Services using relative or absolute urls, e.g:



// GET http://techstacks.io/technology?Slug=ServiceStack
client.get<GetTechnologyResponse>("/technology", { Slug: "ServiceStack" }) 

as well as POST Request DTOs to custom urls:

client.postToUrl("/custom-path", request, { Slug: "ServiceStack" });

client.putToUrl("http://example.org/custom-path", request);

Raw Data Responses

The JsonServiceClient also supports Raw Data responses like string and byte[] which also get a Typed API once declared on Request DTOs using the IReturn<T> marker:

public class ReturnString : IReturn<string> {}
public class ReturnBytes : IReturn<byte[]> {}

Which can then be accessed as normal, with their Response typed to a JavaScript string or Uint8Array for raw byte[] responses:

let str:string = await client.get(new ReturnString());

let data:Uint8Array = await client.get(new ReturnBytes());

Authenticating using Basic Auth

Basic Auth support is implemented in JsonServiceClient and follows the same API made available in the C# Service Clients where the userName/password properties can be set individually, e.g:

var client = new JsonServiceClient(baseUrl);
client.userName = user;
client.password = pass;

const response = await client.get(new SecureRequest());

Or use client.setCredentials() to have them set both together.

Authenticating using Credentials

Alternatively you can authenticate using userName/password credentials by adding a TypeScript Reference to your remote ServiceStack Instance and sending a populated Authenticate Request DTO, e.g:

const response = await client.post(new Authenticate({
    provider: "credentials", userName, password, rememberMe: true }));

This will populate the JsonServiceClient with Session Cookies which will transparently be sent on subsequent requests to make authenticated requests.

Authenticating using JWT

Use the bearerToken property to Authenticate with a ServiceStack JWT Provider using a JWT Token:

client.bearerToken = jwtToken;

Alternatively you can use a Refresh Token instead:

client.refreshToken = refreshToken;

Authenticating using an API Key

Use the bearerToken property to Authenticate with an API Key:

client.bearerToken = apiKey;

Transparently handle 401 Unauthorized Responses

If the server returns a 401 Unauthorized Response either because the client was Unauthenticated or the configured Bearer Token or API Key used had expired or was invalidated, you can use onAuthenticationRequired callback to re-configure the client before automatically retrying the original request, e.g:

client.onAuthenticationRequired = async () => {
    const authClient = new JsonServiceClient(authBaseUrl);
    authClient.userName = userName;
    authClient.password = password;
    const response = await authClient.get(new Authenticate());
    client.bearerToken = response.bearerToken;

//Automatically retries requests returning 401 Responses with new bearerToken
var response = await client.get(new Secured());

Automatically refresh Access Tokens

With the Refresh Token support in JWT you can use the refreshToken property to instruct the Service Client to automatically fetch new JWT Tokens behind the scenes before automatically retrying failed requests due to invalid or expired JWTs, e.g:

//Authenticate to get new Refresh Token
const authClient = new JsonServiceClient(authBaseUrl);
authClient.userName = userName;
authClient.password = password;
const authResponse = await authClient.get(new Authenticate());

//Configure client with RefreshToken
client.refreshToken = authResponse.RefreshToken;

//Call authenticated Services and clients will automatically retrieve new JWT Tokens as needed
const response = await client.get(new Secured());

Use the refreshTokenUri property when refresh tokens need to be sent to a different ServiceStack Server, e.g:

client.refreshToken = refreshToken;
client.refreshTokenUri = authBaseUrl + "/access-token";

ServerEvents Client

The TypeScript ServerEventClient is an idiomatic port of ServiceStack's C# Server Events Client in native TypeScript providing a productive client to consume ServiceStack's real-time Server Events that can be used in TypeScript Web, Node.js Server and React Native iOS and Android Mobile Apps.

const channels = ["home"];
const client = new ServerEventsClient("/", channels, {
    handlers: {
        onConnect: (sub:ServerEventConnect) => {  // Successful SSE connection
            console.log("You've connected! welcome " + sub.displayName);
        onJoin: (msg:ServerEventJoin) => {        // User has joined subscribed channel
            console.log("Welcome, " + msg.displayName);
        onLeave: (msg:ServerEventLeave) => {      // User has left subscribed channel
            console.log(msg.displayName + " has left the building");
        onUpdate: (msg:ServerEventUpdate) => {    // User channel subscription was changed
            console.log(msg.displayName + " channels subscription were updated");
        onMessage: (msg:ServerEventMessage) => {},// Invoked for each other message
        //... Register custom handlers
        announce: (text:string) => {},            // Handle messages with simple argument
        chat: (chatMsg:ChatMessage) => {},        // Handle messages with complex type argument
        CustomMessage: (msg:CustomMessage) => {}, // Handle complex types with default selector
    receivers: { 
        //... Register any receivers
        tv: {
            watch: function (id) {                // Handle 'tv.watch {url}' messages 
                var el = document.querySelector("#tv");
                if (id.indexOf('youtu.be') >= 0) {
                    var v = splitOnLast(id, '/')[1];
                    el.innerHTML = templates.youtube.replace("{id}", v);
                } else {
                    el.innerHTML = templates.generic.replace("{id}", id);
                el.style.display = 'block'; 
            off: function () {                    // Handle 'tv.off' messages
                var el = document.querySelector("#tv");
                el.style.display = 'none';
                el.innerHTML = '';
    onException: (e:Error) => {},                 // Invoked on each Error
    onReconnect: (e:Error) => {}                  // Invoked after each auto-reconnect
.addListener("theEvent",(e:ServerEventMessage) => {}) // Add listener for pub/sub event trigger
.start();                                             // Start listening for Server Events!

When publishing a DTO Type for your Server Events message, your clients will be able to benefit from the generated DTOs in TypeScript ServiceStack References.

Rich intelli-sense support

Even pure HTML/JS Apps that don't use TypeScript or any external dependencies will still benefit from the Server generated dtos.ts and TypeScript definitions where you'll be able to benefit from rich intelli-sense support in smart IDEs like Rider for both the client library:

As well as your App's server generated DTOs: