World Spider Catalog
This primarily a fully searchable online database covering spider taxonomy, but it has a longer history of predecessors which started with Pierre Bonnet (University of Toulouse, France) and Carl Friedrich Roewer (Bremen, Germany). However, if you sign up for a free login, you can have access, via the Bibliography, to a huge number of ID resources for personal use.
Free:
Yes
Available as:
Online
Web link:
Keywords:
spiders