We made the following API updates for March 2026.

Platform API

Order API

Added server-side limit for line items per order

To ensure system stability and optimal performance, we added a server-side limit on the number of line items allowed per order for third-party applications. You can now add up to 2,500 line items to a single order. Requests that exceed this limit return an error.

Affected endpoints:

• Create a new line item
• Create multiple line items
• Create an atomic order

Inventory API

Added support for subcategories

To help merchants organize their inventory more effectively, we updated the Inventory API to support subcategories. You can now group items at a more granular level within an existing parent category.

Affected endpoints:

• Create a subcategory
• Update subcategory information
• Delete a subcategory
• View subcategories in a category
• View items in a subcategory
• Create or delete associations between items and categories

Added server-side limit for bulk inventory updates

To align with the new line item limits and maintain optimal performance, we added a server-side limit for bulk inventory updates for third-party applications. You can now include a maximum of 2,500 items per request.

Affected endpoint: Update existing inventory items

Multiple service charge (MSC) Pilot APIs

Order API

Added server-side limit for line items per order

To ensure system stability and optimal performance, we added a server-side limit on the number of line items allowed per order for third-party applications. You can now add up to 2,500 line items to a single order. Requests that exceed this limit return an error.

Affected endpoints:

• Create a new line item
• Create multiple line items