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We have also implemented a reCAPTCHA option, as an alternative to Facet Restrictions, to verify a user is not a robot when accessing the 4W Facets and the Browse by Category page. ReCAPTCHA is session based and will only display once during a user's session without the need for user interaction. This challenge free method is recommended if you have public collections and want to keep the Who, What, Where, When facets visible in the LUNA Viewer. Enabling reCAPTCHA will override facet restrictions. Read how to implement reCAPTCHA for LUNA.
For non-hosted clients, the reCAPTCHA option may incur costs.