Unlock the app after a web purchase

Identify the buyer on the website

Call identify() once the visitor has an account, before checkout. Their anonymous visit, and the campaign that brought them, become your user.

await voidhash.identify("user_123", { email: "ada@example.com" });

A visitor can also pay before signing up: send voidhash.getDistinctId() instead, and the purchase moves to the user when you call identify() later. See Sell on the web.

Create the Checkout Session with the distinct ID

On your server, put the distinct ID in the session's metadata and, for a subscription, in subscription_data.metadata, so renewals and refunds reach the same person:

import Stripe from "stripe";

const stripe = new Stripe(process.env.STRIPE_SECRET_KEY!);

export async function createCheckout(userId: string) {
  const session = await stripe.checkout.sessions.create({
    mode: "subscription",
    line_items: [{ price: "price_123", quantity: 1 }],
    metadata: { voidhash_distinct_id: userId },
    subscription_data: { metadata: { voidhash_distinct_id: userId } },
    success_url: "https://example.com/get-the-app",
  });
  return session.url;
}

Voidhash grants the perk when Stripe reports the paid invoice. Check the person in People: the subscription and the premium perk appear on user_123.

Send the buyer to the app

On the success page, link to the App Store and Google Play. Store links carry no identity, so the app learns who the person is only when they sign in. Make that easy: use the email from checkout as the login, or send a one-time sign-in link from your backend. To be told when a purchase lands, subscribe a webhook to subscription.created.

Identify in the app and check the perk

After sign-in, identify with the same user ID, then check the perk. identify refreshes the person, so the web purchase is there on the first screen.

try await voidhash.identify(externalUserId: "user_123")
let hasPremium = try await voidhash.getCurrentPerson()?.hasActivePerk("premium") ?? false

voidhash.identify(externalUserId = "user_123")
val hasPremium = voidhash.getCurrentPerson()?.hasActivePerk("premium") == true

await voidhash.client.identify("user_123");
const result = await voidhash.client.hasPerk("premium");