Prefill

Prefill refers to the act of populating data fields or documents with information before a user or process requires them. In computing and information systems, prefill is used to streamline forms and workflows by providing known values automatically. It is distinct from autofill, where the user triggers completion of fields, whereas prefill is typically applied at the time a form is loaded or generated.

In user interfaces, prefill sources include a user profile, prior submissions, cookies, session data, or external databases. Prefill can occur on page load, during template rendering, or when a form is created from a data model. It helps users review and update existing data rather than re-enter it from scratch. Prefill is commonly used in ecommerce checkout, registration forms, and survey tools.

Data handling for prefill involves sourcing accurate data, ensuring data minimization, and respecting consent and privacy. Techniques include server-side rendering of forms with embedded values, or client-side scripting that fills fields after the page loads. Developers must consider security implications, such as protecting sensitive data and avoiding leakage in shared devices.

In medicine, the term prefill is also used in reference to prefilled medication delivery devices, such as prefilled syringes, which are supplied with a set dose to simplify administration and reduce preparation time.

Limitations include the risk of presenting outdated or incorrect information, forcing users to correct data, and potential privacy concerns. Best practices emphasize validation, user review, and secure, auditable data sources.