---
title: TanStack Start
description: Set up your first durable workflow in a TanStack Start application.
type: guide
summary: Set up Workflow SDK in a TanStack Start app.
prerequisites:
- /docs/getting-started
related:
- /docs/foundations/workflows-and-steps
---
Set up your first durable workflow in a TanStack Start app and learn the core Workflow SDK concepts.
---
## Create your TanStack Start project
Start by creating a new TanStack Start project:
```bash
npx @tanstack/cli create my-workflow-app
```
Enter the newly made directory:
```bash
cd my-workflow-app
```
### Install `workflow`
```package-install
npm i workflow
```
### Configure TanStack Start
TanStack Start runs on Vite, so the Workflow SDK is wired in via the same `workflow/vite` plugin. Add `workflow()` to the existing `plugins` array in your Vite config. List it first so the `"use workflow"` and `"use step"` transforms run before any other plugin processes the file.
```typescript title="vite.config.ts" lineNumbers
import { defineConfig } from "vite";
import { workflow } from "workflow/vite";
// ...
export default defineConfig({
plugins: [
workflow(), // [!code highlight]
// ...the existing tanstackStart(), nitro(), and any other plugins
],
});
```
### Set up IntelliSense for TypeScript (optional)
To enable helpful hints in your IDE, set up the workflow plugin in `tsconfig.json`:
```json title="tsconfig.json" lineNumbers
{
"compilerOptions": {
// ... rest of your TypeScript config
"plugins": [
{
"name": "workflow" // [!code highlight]
}
]
}
}
```
## Create your first workflow
Create a new file for our first workflow:
```typescript title="src/workflows/user-signup.ts" lineNumbers
import { sleep } from "workflow";
export async function handleUserSignup(email: string) {
"use workflow"; // [!code highlight]
const user = await createUser(email);
await sendWelcomeEmail(user);
await sleep("5s"); // Pause for 5s - doesn't consume any resources
await sendOnboardingEmail(user);
return { userId: user.id, status: "onboarded" };
}
```
We'll fill in those functions next, but first review this code:
* We define a **workflow** function with the directive `"use workflow"`. Think of the workflow function as the _orchestrator_ of individual **steps**.
* The Workflow SDK's `sleep` function allows us to suspend execution of the workflow without using up any resources. A sleep can be a few seconds, hours, days, or even months long.
## Create your workflow steps
Define the missing functions.
```typescript title="src/workflows/user-signup.ts" lineNumbers
import { FatalError } from "workflow"
// Our workflow function defined earlier
async function createUser(email: string) {
"use step"; // [!code highlight]
console.log(`Creating user with email: ${email}`);
// Full Node.js access - database calls, APIs, etc.
return { id: crypto.randomUUID(), email };
}
async function sendWelcomeEmail(user: { id: string; email: string; }) {
"use step"; // [!code highlight]
console.log(`Sending welcome email to user: ${user.id}`);
if (Math.random() < 0.3) {
// By default, steps will be retried for unhandled errors
throw new Error("Retryable!");
}
}
async function sendOnboardingEmail(user: { id: string; email: string}) {
"use step"; // [!code highlight]
if (!user.email.includes("@")) {
// To skip retrying, throw a FatalError instead
throw new FatalError("Invalid Email");
}
console.log(`Sending onboarding email to user: ${user.id}`);
}
```
Taking a look at this code:
* Business logic lives inside **steps**. When a workflow invokes a step, the workflow suspends while the step runs with full Node.js access. The combined handler may execute it inline; queued retries and continuations return through the same flow route.
* If a step throws an error, like in `sendWelcomeEmail`, the step will automatically be retried until it succeeds (or hits the step's max retry count).
* Steps can throw a `FatalError` if an error is intentional and should not be retried.
We'll dive deeper into workflows, steps, and other ways to suspend or handle events in [Foundations](/docs/foundations).
## Create your route handler
To invoke your new workflow, add a server handler at `src/routes/api/signup.ts`:
```typescript title="src/routes/api/signup.ts"
import { createFileRoute } from "@tanstack/react-router";
import { json } from "@tanstack/react-start";
import { start } from "workflow/api";
import { handleUserSignup } from "../../workflows/user-signup";
export const Route = createFileRoute("/api/signup")({
server: {
handlers: {
POST: async ({ request }) => {
const { email } = await request.json();
// Executes asynchronously and doesn't block your app
await start(handleUserSignup, [email]);
return json({ message: "User signup workflow started" });
},
},
},
});
```
This route handler creates a `POST` request endpoint at `/api/signup` that will trigger your workflow.
Workflows can be triggered from API routes or any server-side code.
## Run in development
To start your development server, run the following command in your terminal in the TanStack Start root directory:
```bash
npm run dev
```
Once your development server is running, you can trigger your workflow by running this command in the terminal:
```bash
curl -X POST --json '{"email":"hello@example.com"}' http://localhost:3000/api/signup
```
Check the dev server logs to see your workflow execute as well as the steps that are being processed.
Additionally, you can use the [Workflow SDK CLI or Web UI](/docs/observability) to inspect your workflow runs and steps in detail.
```bash
# Open the observability Web UI on http://localhost:3456
npx workflow web
# or if you prefer a terminal interface, use the CLI inspect command
npx workflow inspect runs
```
---
## Deploying to production
Workflow SDK apps currently work best when deployed to [Vercel](https://vercel.com/home) and need no special configuration.
Check the [Deploying](/docs/deploying) section to learn how your workflows can be deployed elsewhere.
## Next steps
* Learn more about the [Foundations](/docs/foundations).
* Check [Errors](/docs/errors) if you encounter issues.
* Explore the [API Reference](/docs/api-reference).