With Harrogate being historically in the West Riding of Yorkshire, the West Yorkshire Archive Service hold many records about Harrogate and the surrounding area at their Leeds, Bradford and Wakefield offices. The main website is http://www.wyjs.org.uk/archive-services. For an overview go to the collections guides see https://www.wyjs.org.uk/archive-service/our-collections/guides-to-our-collections/. The best way to search for records about Harrogate is to start with a search in the online catalogue here https://www.catalogue.wyjs.org.uk/calmview/. The Leeds branch is at Morley; phone and email contacts above. At Leeds you will find, for example, registers from Harrogate Christ Church, St Luke and St Mark, as well as family and estate papers, sale catalogues and maps and plans, including a wonderful map dated 1767 of the Forest of Knaresborough.