This guide outlines considerations when migrating from the online store to Hydrogen. ## Shared carts Online store carts are compatible with the Storefront API and vice versa, making it possible to share carts between channels. Both Liquid and Hydrogen cart IDs are stored in a `cart` cookie, which prevents customers from losing carts when migrating to or from Hydrogen. <figure class="figure"><img src="https://cdn.shopify.com/shopifycloud/shopify_dev/assets/custom-storefronts/hydrogen/hydrogen-liquid-shared-cart-cookie-95369c85a1fc733825433ebbd958541b4ee756363490071700bd663d8505ba31.png" class="lazyload" alt="Developer tools in a browser showing Cookies, with a cart cookie" width="1396" height="146"></figure> ## Subdomain for checkout Regardless of whether you're using the online store or Hydrogen, customers are always directed back to a Shopify-hosted checkout. Traditionally, a checkout URL might look something like `{shop}.myshopify.com/123456/checkouts…`. To make sure your Hydrogen site works correctly, assign a subdomain for your storefront to checkout. For example, if your Hydrogen store is `example.com`, then assign `checkout.example.com` to checkout. To do this: 1. [Connect the subdomain](https://help.shopify.com/en/manual/domains/add-a-domain/connecting-domains/connect-subdomain) 1. Set the **Target** to **Online Store**. 1. Set the **Domain** type to **Primary**. ## Configure routing When you're migrating from Themes to Headless, you can define your own routes. For example, you might set the route that your cart is on at `example.com/bag` instead of `example.com/cart`. To make sure that backlinks continue to work correctly, make sure you set up redirects for any customized routes. The following is an example of setting up a redirect from `/cart`: <p> <div class="react-code-block" data-preset="file"> <div class="react-code-block-preload ThemeMode-dim"> <div class="react-code-block-preload-bar "></div> <div class="react-code-block-preload-placeholder-container"> <div class="react-code-block-preload-code-container"> <div class="react-code-block-preload-codeline-number"></div> <div class="react-code-block-preload-codeline"></div> </div> <div class="react-code-block-preload-code-container"> <div class="react-code-block-preload-codeline-number"></div> <div class="react-code-block-preload-codeline"></div> </div> <div class="react-code-block-preload-code-container"> <div class="react-code-block-preload-codeline-number"></div> <div class="react-code-block-preload-codeline"></div> </div> <div class="react-code-block-preload-code-container"> <div class="react-code-block-preload-codeline-number"></div> <div class="react-code-block-preload-codeline"></div> </div> <div class="react-code-block-preload-code-container"> <div class="react-code-block-preload-codeline-number"></div> <div class="react-code-block-preload-codeline"></div> </div> <div class="react-code-block-preload-code-container"> <div class="react-code-block-preload-codeline-number"></div> <div class="react-code-block-preload-codeline"></div> </div> </div> </div> <script data-option="filename" data-value="/app/routes/cart.jsx"></script> <script type="text/plain" data-language="jsx"> RAW_MD_CONTENT// Catch `/cart` and redirect to `/bag` import {redirect} from '@shopify/remix-oxygen'; export function loader() { return redirect('/bag'); } END_RAW_MD_CONTENT</script> </div> </p> ## Online store redirects and canonical links To make sure any backlinks, such as from integrations, send traffic to your Hydrogen storefront and not your Liquid-based Online Store, be sure to set up redirects to take customers to your Hydrogen storefront. For more information, refer to our [redirect traffic](/docs/storefronts/headless/hydrogen/migrate/redirect-traffic) doc. ## Product feeds If you use Shopify's out-of-the-box product feeds, then you'll need to set up feed rules (for example, [Facebook](https://www.facebook.com/business/help/1206652516201625?id=725943027795860) and [Google](https://support.google.com/merchants/answer/7450276?hl=en)) to use your Hydrogen storefront's domain. ## Password protection Online store password protection prevents Hydrogen checkouts. To remove password protection, do the following: 1. From the Shopify admin, under **Sales channels**, click **Online Store** > **Preferences**. 1. In the **Restrict store access** section, deselect **Restrict access to visitors with the password**. 1. Click **Save**. ## Notifications You can update notifications to use the same domain as your Hydrogen storefront. 1. From the Shopify admin, click **Settings** > **Notifications**. 1. Update the **Notification URLs** setting. ## Next Steps - [Go live with Hydrogen](/docs/storefronts/headless/hydrogen/production-checklist#go-live-guide) for merchants ready to publish their new Hydrogen storefront.