Node.js Quick Start

In this tutorial you will add Inngest to a Node.js app to easily run background tasks and build complex workflows.

Inngest makes it easy to build, manage, and execute durable functions. Some use cases include scheduling drip marketing campaigns, building payment flows, or chaining LLM interactions.

By the end of this ten-minute tutorial you will:

• Set up and run Inngest on your machine.
• Write your first Inngest function.
• Trigger your function from your app and through Inngest Dev Server.

Let's get started!

Select your Node.js framework

Choose your preferred Node.js web framework to get started. This guide uses ESM (ECMAScript Modules), but it also works for Common.js with typical modifications.

Inngest works with any Node, Bun or Deno backend framework,but this tutorial will focus on some of the most popular frameworks.

Optional: Use a starter project

If you don't have an existing project, you can clone the following starter project to run through the quick start tutorial:

Starting your project

Start your server using your typical script. We recommend using something like tsx or nodemon for automatically restarting on file save:

npx tsx watch ./index.ts # replace with your own main entrypoint file

Now let's add Inngest to your project.

1. Install the Inngest SDK

In your project directory's root, run the following command to install Inngest SDK:

npm install inngest

2. Run the Inngest Dev Server

Next, start the Inngest Dev Server, which is a fast, in-memory version of Inngest where you can quickly send and view events events and function runs. This tutorial assumes that your Express.js server will be running on port 3000; change this to match your port if you use another.

npx inngest-cli@latest dev -u http://localhost:3000/api/inngest

$ npx inngest-cli@latest dev -u http://localhost:3000/api/inngest

12:33PM INF executor > service starting
12:33PM INF runner > starting event stream backend=redis
12:33PM INF executor > subscribing to function queue
12:33PM INF runner > service starting
12:33PM INF runner > subscribing to events topic=events
12:33PM INF no shard finder;  skipping shard claiming
12:33PM INF devserver > service starting
12:33PM INF devserver > autodiscovering locally hosted SDKs
12:33PM INF api > starting server addr=0.0.0.0:8288

        Inngest dev server online at 0.0.0.0:8288, visible at the following URLs:

         - http://127.0.0.1:8288 (http://localhost:8288)

        Scanning for available serve handlers.
        To disable scanning run `inngest dev` with flags: --no-discovery -u <your-serve-url>

In your browser open http://localhost:8288 to see the development UI where later you will test the functions you write:

3. Create an Inngest client

Inngest invokes your functions securely via an API endpoint at /api/inngest. To enable that, you will create an Inngest client in your project, which you will use to send events and create functions.

Create a file in the directory of your preference. We recommend creating an inngest directory for your client and all functions.

import { Inngest } from "inngest";

// Create a client to send and receive events
export const inngest = new Inngest({ id: "my-app" });

// Create an empty array where we'll export future Inngest functions
export const functions = [];

4. Set up the Inngest http endpoint

Using your existing Express.js server, we'll set up Inngest using the provided serve handler which will "serve" Inngest functions. Here we'll assume this file is your entrypoint at inngest.ts and all import paths will be relative to that:

import express from "express";
import { serve } from "inngest/express";
import { inngest, functions } from "./src/inngest"

// Important: ensure you add JSON middleware to process incoming JSON POST payloads.
app.use(express.json());
// Set up the "/api/inngest" (recommended) routes with the serve handler
app.use("/api/inngest", serve({ client: inngest, functions }));

app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

5. Write your first Inngest function

In this step, you will write your first durable function. This function will be triggered whenever a specific event occurs (in our case, it will be test/hello.world). Then, it will sleep for a second and return a "Hello, World!".

To define the function, use the createFunction method on the Inngest client.

Define a function in the same file where we defined our Inngest client:

import { Inngest } from "inngest";

export const inngest = new Inngest({ id: "my-app" });

// Your new function:
const helloWorld = inngest.createFunction(
  { id: "hello-world" },
  { event: "test/hello.world" },
  async ({ event, step }) => {
    await step.sleep("wait-a-moment", "1s");
    return { message: `Hello ${event.data.email}!` };
  },
);

// Add the function to the exported array:
export const functions = [
  helloWorld
];

Now, it's time to run your function!

5. Trigger your function from the Inngest Dev Server UI

You will trigger your function in two ways: first, by invoking it directly from the Inngest Dev Server UI, and then by sending events from code.

With your Express.js server and Inngest Dev Server running, open the Inngest Dev Server UI and select the "Functions" tab http://localhost:8288/functions. You should see your function. (Note: if you don't see any function, select the "Apps" tab to troubleshoot)

To trigger your function, use the "Invoke" button for the associated function:

In the pop up editor, add your event payload data like the example below. This can be any JSON and you can use this data within your function's handler. Next, press the "Invoke Function" button:

{
  "data": {
    "email": "test@example.com"
  }
}

The payload is sent to Inngest (which is running locally) which automatically executes your function in the background! You can see the new function run logged in the "Runs" tab:

When you click on the run, you will see more information about the event, such as which function was triggered, its payload, output, and timeline:

In this case, the payload triggered the hello-world function, which did sleep for a second and then returned "Hello, World!". No surprises here, that's what we expected!

To aid in debugging your functions, you can quickly "Rerun" or "Cancel" a function. Try clicking "Rerun" at the top of the "Run details" table:

After the function was replayed, you will see two runs in the UI:

Now you will trigger an event from inside your app.

6. Trigger from code

Inngest is powered by events.

To trigger Inngest functions to run in the background, you will need to send events from your application to Inngest. Once the event is received, it will automatically invoke all functions that are configured to be triggered by it.

To send an event from your code, you can use the Inngest client's send() method.

You will now send an event from within your server from a /api/hello GET endpoint. Create a new get handler on your server object:

import express from "express";
import { serve } from "inngest/express";
import { inngest, functions } from "./src/inngest"

app.use(express.json());
app.use("/api/inngest", serve({ client: inngest, functions }));

// Create a new route
app.get("/api/hello", async function (req, res, next) {
  await inngest.send({
    name: "test/hello.world",
    data: {
      email: "testUser@example.com",
    },
  }).catch(err => next(err));
  res.json({ message: 'Event sent!' });
});

app.listen(3000, () => {
  console.log('Server running on http://localhost:3000');
});

Every time this API route is requested, an event is sent to Inngest. To test it, open http://localhost:3000/api/hello (change your port if your Express.js app is running elsewhere). You should see the following output: {"message":"Event sent!"}

If you go back to the Inngest Dev Server, you will see a new run is triggered by this event:

And - that's it! You now have learned how to create Inngest functions and you have sent events to trigger those functions. Congratulations 🥳

Next Steps

To continue your exploration, feel free to check out:

• Examples of what other people built with Inngest.
• Case studies showcasing a variety of use cases.
• Our blog where we explain how Inngest works, publish guest blog posts, and share our learnings.

You can also read more:

• About Inngest functions.
• About Inngest steps.
• About Durable Execution
• How to use Inngest with other frameworks.
• How to deploy your app to your platform.