Sometimes it might be more convenient for an author or editor to work with an indexer who is a member of another indexing society. Note that not all indexing societies restrict their online directories to people with indexing qualifications, and you should therefore check that members of other societies have relevant skills and experience.
The following organisations are affiliated to, or associate members of, ICRIS, the International Committee of Representatives of Indexing Societies. The links will take you to the directory or listing page.
AFEPI Ireland (Association of Editors, Proofreaders and Indexers of Ireland)
ANZSI (Australian and New Zealand Society of Indexers)
ASAIB (Association of Southern African Indexers and Bibliographers)
ASI (American Society for Indexing)
DNI (Deutsches Netzwerk der Indexer/German Indexing Network)
NIN (Nederlands Indexers Netwerk/Netherlands Indexing Network)