Thicket16 is a card-catalogue index of the open web — a methodically assembled collection of 833 sites organised across 22 subject headings and maintained for public reference. The catalogue was assembled on the principle that the web is easier to navigate when its contents are organised by subject rather than by popularity rank or advertising budget. Each entry in the Thicket16 collection is filed under the heading that best reflects the site's primary activity, with a brief description drawn from the owner's submission. Browsing the catalogue is free. Visitors may move between subject headings, read entry descriptions, and follow links to listed sites without registering or providing personal information. The collection spans a wide range of subject matter, from specialist trade services to creative and cultural platforms. New additions are welcomed. Site owners may submit any active domain by completing the short form on the submission page. Submitted entries are reviewed by catalogue staff before filing. The review process considers whether the site is active, whether its description is accurate, and which subject heading best suits it. Thicket16 is maintained as a reference index. It does not sell placement within subject headings, accept payment for priority review, or operate a commercial listing programme. The catalogue exists to be used.