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What is a Return/Redirect URL?

Return and Redirect URLs, are urls that your customer will be redirected to, after a successful payment. They contain important information signed by creem, that you can use to verify the payment and the user. Using these URLs, you can create a seamless experience for your users, by redirecting them back to your website after a successful payment.
You have the optionality to use the information in the URL query parameters, or to use webhooks to receive updates on your application automatically, or both.

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How to set a Return/Redirect URL

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What is included on the Return URL?

A return URL will always contain the following query parameters, and will look like the following:
https://yourwebsite.com?checkout_id=ch_1QyIQDw9cbFWdA1ry5Qc6I&order_id=ord_4ucZ7Ts3r7EhSrl5yQE4G6&customer_id=cust_2KaCAtu6l3tpjIr8Nr9XOp&subscription_id=sub_ILWMTY6uBim4EB0uxK6WE&product_id=prod_6tW66i0oZM7w1qXReHJrwg&signature=044bd1691d254c4ad4b31b7f246330adf09a9f07781cd639979a288623f4394c?
Query parameterDescription
checkout_idThe ID of the checkout session created for this payment.
order_idThe ID of the order created after successful payment.
customer_idThe customer ID, based on the email that executed the successful payment.
subscription_idThe subscription ID of the product.
product_idThe product ID that the payment is related to.
request_idOptional The request ID you provided when creating this checkout session.
signatureAll previous parameters signed by creem using your API-key, verifiable by you.

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How to verify Creem signature?

To verify the signature, you can use the following code snippet: 
export interface RedirectParams {
  request_id?: string | null;
  checkout_id?: string | null;
  order_id?: string | null;
  customer_id?: string | null;
  subscription_id?: string | null;
  product_id?: string | null;
}

  private generateSignature(params: RedirectParams, apiKey: string): string {
    const data = Object.entries(params)
      .map(([key, value]) => `${key}=${value}`)
      .concat(`salt=${apiKey}`)
      .join('|');
    return crypto.createHash('sha256').update(data).digest('hex');
  }
In summary, concatenate all parameters and the salt (your API-key) with a | separator, and hash it using SHA256. This will generate a signature that you can compare with the signature provided in the URL.