# Custom Fields The E-Commerce Payment Gateway (EGW) allows merchants to create Custom Fields to collect additional information from customers during the payment process. Custom Fields enable merchants to include merchant-specific data fields in payment links or checkout pages, helping capture important information related to the transaction. **Merchants can use Custom Fields to:** * collect customer information during checkout * include order references or internal transaction identifiers * capture delivery details or additional order information * attach metadata to payments for reporting or reconciliation **Custom Fields can be:** * pre-filled by the merchant when generating a payment link; or * completed by the customer during the checkout process. **The gateway supports flexible configuration options, including:** * mandatory or optional fields * input validation rules (such as minimum or maximum length) * multilingual field labels for customer-facing forms * display of fields within the secure hosted checkout page All captured values are stored as transaction metadata, enabling merchants to associate additional context with each payment while maintaining a seamless checkout experience. --- # Agent Instructions: Querying This Documentation If you need additional information that is not directly available in this page, you can query the documentation dynamically by asking a question. Perform an HTTP GET request on the current page URL with the `ask` query parameter: ``` GET https://doc.ecomm.api.tietoevry.com/features/custom-fields.md?ask= ``` The question should be specific, self-contained, and written in natural language. The response will contain a direct answer to the question and relevant excerpts and sources from the documentation. Use this mechanism when the answer is not explicitly present in the current page, you need clarification or additional context, or you want to retrieve related documentation sections.