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If you want to integrate more deeply the checkout process with your website or application, you can use our dedicated API. The first step is to create a Checkout session. For this you’ll need at least your Product ID. You can retrieve your Product ID from Products in your dashboard, click on “context-menu” button in front of your product and click on Copy Product ID. The API will return you an object containing all the information about the session, including an URL where you should redirect your customer so they can complete their order.

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Multiple products

You can create a checkout session with multiple products. This is useful if you want to allow your customers to choose between different products before they checkout.

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Ad-hoc prices

For advanced use cases where you need complete control over pricing, you can create ad-hoc prices directly when creating a checkout session. Ad-hoc prices are temporary prices that exist only for that specific checkout session and don’t appear in your product’s catalog. This is useful when you need to:
  • Apply dynamic pricing based on user-specific factors
  • Create custom pricing tiers for specific customers
  • Implement usage-based or calculated pricing that varies per checkout
  • Test pricing variations without modifying your product catalog
When creating a checkout session, you can pass a prices parameter that maps product IDs to an array of price definitions. These prices will be created on-the-fly and associated with the checkout session.
Ad-hoc prices are marked with source: "ad_hoc" in the API response, while catalog prices have source: "catalog". Ad-hoc prices are temporary and specific to the checkout session.

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Example

import { Polar } from "@polar-sh/sdk";

const polar = new Polar({
  accessToken: process.env["POLAR_ACCESS_TOKEN"] ?? "",
});

async function run() {
  const checkout = await polar.checkouts.create({
    products: ["productId"],
    prices: {
      "productId": [
        {
          amountType: "fixed",
          priceAmount: 10000, // $100.00
          priceCurrency: "usd",
        }
      ]
    }
  });

  console.log(checkout.url);
}

run();

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Price types

Ad-hoc prices support all the same price types as catalog prices:
  • Fixed: A fixed amount price
  • Custom: Pay-what-you-want pricing
  • Free: No charge
  • Seat-based: Pricing based on number of seats
  • Metered: Usage-based pricing tied to a meter
For the complete schema of each price type, refer to the Checkout API reference.

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External Customer ID

Quite often, you’ll have your own users management system in your application, where your customer already have an ID. To ease reconciliation between Polar and your system, you can inform us about your customer ID when creating a checkout session through the external_customer_id field. After a successful checkout, we’ll create a Customer on Polar with the external ID you provided. It’ll be provided through the customer.external_id property in webhooks you may have configured.

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SDK examples

Using our SDK, creating a checkout session is quite straightforward. 
import { Polar } from "@polar-sh/sdk";

const polar = new Polar({
  accessToken: process.env["POLAR_ACCESS_TOKEN"] ?? "",
});

async function run() {
  const checkout = await polar.checkouts.create({
    products: ["productId"]
  });

  console.log(checkout.url)
}

run();