@fourierhq/sdk

Open source product analytics SDK. Drop-in compatible with Segment's analytics.js API: identify, track, page, group, alias, reset, user(), ready(), on(), trackLink, trackForm, source middleware and the same ajs_* cookies, so an existing Segment install keeps its anonymous ids.

It talks to a Fourier server you run yourself — self-hosted or on Vercel, with ClickHouse underneath. The SDK is MIT; the server is AGPL-3.0.

pnpm add @fourierhq/sdk

Next.js (App Router)

// app/layout.tsx
import { FourierProvider } from "@fourierhq/sdk/next";

export default function RootLayout({ children }) {
  return (
    <html>
      <body>
        <FourierProvider writeKey={process.env.NEXT_PUBLIC_FOURIER_WRITE_KEY!} host={process.env.NEXT_PUBLIC_FOURIER_HOST!}>
          {children}
        </FourierProvider>
      </body>
    </html>
  );
}

"use client";
import { useFourier } from "@fourierhq/sdk/next";

export function UpgradeButton() {
  const fourier = useFourier();
  return <button onClick={() => fourier.track("Upgrade Clicked", { plan: "pro" })}>Upgrade</button>;
}

Page views are tracked automatically on route changes.

Anywhere in the browser

import fourier from "@fourierhq/sdk";
fourier.init({ writeKey: "...", host: "https://analytics.example.com" });
fourier.identify("user_123", { email: "[email protected]", plan: "pro" });
fourier.group("acme", { name: "Acme Inc", plan: "enterprise" });
fourier.track("Report Exported", { format: "csv" });

Server (API routes, server actions, cron)

import { FourierServer } from "@fourierhq/sdk/server";
const fourier = new FourierServer({ writeKey: process.env.FOURIER_WRITE_KEY!, host: process.env.FOURIER_HOST! });
fourier.track({ userId: "user_123", event: "Invoice Paid", properties: { amount: 4900 } });
await fourier.closeAndFlush();

Several sites, one identity

fourier.init({
  writeKey,                       // this site's own source key from the dashboard
  host,
  cookieDomain: ".example.com",   // subdomains share the anonymous id via the cookie
  crossDomain: ["example.io"],    // links to other domains carry it as ?ajs_aid=… (and ?ajs_uid=… when identified)
});
fourier.decorateUrl("https://app.example.io/signup"); // for URLs you build yourself
fourier.newSession();                                  // force a new session (attribution touch)

Companies / workspaces

group(groupId, traits) registers a company and links the current user to it. Every subsequent event carries context.groupId, so the dashboard and the query API can roll users and events up by company.