@profullstack/referrals

Referral program SDK with an 80/20 split: 60% commission to the affiliate, 20% discount to the new customer.

Install

npm install @profullstack/referrals

Split

Party	Value
Affiliate	60%
New customer	20%
Total	80%

Core (framework-agnostic)

import {
  DEFAULT_SPLIT,
  createCode,
  validateCode,
  applyReferral,
  calculateReferral,
  buildReferralUrl,
  extractCode,
} from "@profullstack/referrals";

// Create a referral code for a user
const code = await createCode("user-123", store);
// → { code: "AB3K7PQZ", ownerId: "user-123", ... }

// Build a shareable link
const link = buildReferralUrl("https://myapp.com/signup", code.code);
// → "https://myapp.com/signup?ref=AB3K7PQZ"

// Calculate discount + commission for $99.00
const calc = calculateReferral(9900);
// → { discountCents: 1980, commissionCents: 5940, finalAmountCents: 7920 }

// Apply the referral when the new user pays
const usage = await applyReferral({
  code: "AB3K7PQZ",
  newUserId: "new-user-456",
  amountCents: 9900,
  store,
});

Implementing ReferralStore

The core functions take a ReferralStore — wire it to your database:

import type { ReferralStore } from "@profullstack/referrals";
import { supabase } from "@/lib/supabase";

export const referralStore: ReferralStore = {
  async saveCode(code) {
    await supabase.from("referral_codes").insert(code);
  },
  async getCode(code) {
    const { data } = await supabase
      .from("referral_codes")
      .select("*")
      .eq("code", code)
      .maybeSingle();
    return data;
  },
  async saveUsage(usage) {
    await supabase.from("referral_usages").insert(usage);
  },
  async getUsagesByAffiliate(affiliateId) {
    const { data } = await supabase
      .from("referral_usages")
      .select("*")
      .eq("affiliate_id", affiliateId);
    return data ?? [];
  },
};

React

import { ReferralProvider, useReferral, ReferralBanner, CopyReferralButton } from "@profullstack/referrals/react";

// Wrap your app (reads ?ref= from URL automatically)
<ReferralProvider>
  <App />
</ReferralProvider>

// Show discount banner during checkout
<ReferralBanner amountCents={9900} currencySymbol="$" />
// → "Referral discount applied: 20% off — you save $19.80"

// Affiliate share button
<CopyReferralButton code={myCode} baseUrl="https://myapp.com/signup" />

Next.js App Router

app/api/referrals/route.ts

import { makeReferralHandlers } from "@profullstack/referrals/next";
import { referralStore } from "@/lib/referral-store";
import { getUser } from "@/lib/auth";

export const { GET, POST } = makeReferralHandlers({
  store: referralStore,
  getUserId: async (req) => {
    const user = await getUser(req);
    return user?.id ?? null;
  },
});

middleware.ts — persist the ?ref= code in a cookie across page navigations:

import { NextResponse } from "next/server";
import { trackReferralCode } from "@profullstack/referrals/next";

export function middleware(request) {
  return trackReferralCode(request, NextResponse.next());
}

API routes

Method	Params	Description
GET	?action=validate&ref=CODE	Check if a code is valid
GET	?action=mycode	Get current user's referral usages
POST	{ action: "create" }	Create a new referral code
POST	{ action: "apply", code, amount }	Apply a code to a purchase

Publishing to npm

cd ~/src/referrals
npm login   # one-time
npm publish --access public

Then update the dependency in each project from file:../referrals to ^0.1.0.