npm install inngest

import { Inngest } from "inngest";

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

// Simple background function
export const sendWelcomeEmail = inngest.createFunction(
 { id: "send-welcome-email" },
 { event: "user/created" },
 async ({ event, step }) => {
 // Step 1: Send welcome email
 await step.run("send-email", async () => {
 await emailService.send({
 to: event.data.email,
 template: "welcome",
 name: event.data.name,
 });
 });

 // Step 2: Wait 3 days
 await step.sleep("wait-3-days", "3 days");

 // Step 3: Send follow-up
 await step.run("send-followup", async () => {
 await emailService.send({
 to: event.data.email,
 template: "getting-started",
 });
 });

 // Step 4: Wait 7 more days, then check engagement
 await step.sleep("wait-7-days", "7 days");

 const isActive = await step.run("check-engagement", async () => {
 return await analytics.isUserActive(event.data.userId);
 });

 if (!isActive) {
 await step.run("send-reengagement", async () => {
 await emailService.send({
 to: event.data.email,
 template: "we-miss-you",
 });
 });
 }
 }
);

// From your API route
await inngest.send({
 name: "user/created",
 data: {
 userId: user.id,
 email: user.email,
 name: user.name,
 },
});

// app/api/inngest/route.ts
import { serve } from "inngest/next";
import { inngest } from "@/lib/inngest";
import { sendWelcomeEmail } from "@/inngest/functions";

export const { GET, POST, PUT } = serve({
 client: inngest,
 functions: [sendWelcomeEmail],
});

export const dailyReport = inngest.createFunction(
 { id: "daily-report" },
 { cron: "0 9 * * *" }, // Every day at 9 AM
 async ({ step }) => {
 const metrics = await step.run("fetch-metrics", async () => {
 return await analytics.getDailyMetrics();
 });

 await step.run("send-report", async () => {
 await slack.postMessage({
 channel: "#metrics",
 text: formatReport(metrics),
 });
 });
 }
);

export const processOrder = inngest.createFunction(
 {
 id: "process-order",
 concurrency: { limit: 10 }, // Max 10 concurrent
 throttle: { limit: 100, period: "1m" }, // Max 100/minute
 retries: 3,
 },
 { event: "order/placed" },
 async ({ event, step }) => {
 // Process with automatic retry on failure
 await step.run("charge", () => payment.charge(event.data));
 await step.run("fulfill", () => warehouse.ship(event.data));
 await step.run("notify", () => email.sendConfirmation(event.data));
 }
);

export const processCSV = inngest.createFunction(
 { id: "process-csv" },
 { event: "csv/uploaded" },
 async ({ event, step }) => {
 const rows = await step.run("parse", async () => {
 return await parseCSV(event.data.fileUrl);
 });

 // Fan out: send an event for each row
 await step.sendEvent(
 "fan-out",
 rows.map((row) => ({
 name: "csv/row-process",
 data: row,
 }))
 );
 }
);