Pre-load cart with subscription/plan products using permalinks

Store Design

Topic summary

Core Issue:
Users are trying to pre-load Shopify carts with subscription products using URL parameters, specifically including selling_plan IDs alongside variant IDs.

Working Solution:
Phillip_Malboeu provided a functional URL structure:

https://{SHOP}.myshopify.com/cart/clear?return_to=/cart/add?items[][id]={VARIANT_ID}%26items[][quantity]={QUANTITY}%26items[][selling_plan]{SELLING_PLAN_ID}%26return_to=/checkout

Key Technical Details:

  • The items[][] array syntax is critical for passing multiple parameters to the server
  • %26 represents URL-encoded ampersands (&)
  • Multiple products can be added by repeating the items[][id] pattern
  • Remove %26return_to=/checkout to redirect to cart page instead of checkout
  • Both subscription and non-subscription products can coexist in the same cart

Ongoing Challenges:

  • Discount codes: Multiple users report that appending %26discount=CODE to the URL doesn’t auto-apply discount codes at checkout, even though manual entry works
  • Redirect issues: Some users experience unexpected redirects to homepage after checkout instead of intended destinations

The solution is based on Shopify’s Cart Ajax API documentation.

Summarized with AI on November 9. AI used: claude-sonnet-4-5-20250929.
36

When I try this pattern I get an error: “Parameter Missing or Invalid: Required parameter missing or invalid: items”.

It’s pretty important to the flow that I’m trying to manage that I’m also able to clear the cart as well but haven’t been able to find a permalink combination of cart clear / cart add / set discount (that supports subscriptions) that is working. Has anyone had any luck with this combination?