General Philosophy Guide

A "comprehensive index and bibliography of philosophy maintained by the community of philosophers." PhilPapers monitors "all sources of research content in philosophy, including journals, books, open access archives, and personal pages maintained by academics" (website).

Major works in the history of ethics from Ethics Updates

A digital library of ancient Greece and Rome (and much more). Includes primary texts in ancient philosophy, as well as Greek and Latin lexicons.

An electronic archive for preprints in the philosophy of science. The goal of the archive is to promote communication in the field by the rapid dissemination of new work.

Includes a digital version of the German critical edition of the complete works of Nietzsche and a digital facsimile reproduction of the entire Nietzsche estate, including first editions of works, manuscripts, letters, and biographical documents.

Online electronic texts of literature and reference works, available free of charge.

A dynamic reference work covering all areas in the field of philosophy, evolving, and adapting in response to new research.

The Internet Encyclopedia of Philosophy (IEP) was founded in 1995 as a non-profit organization to provide open access to detailed, scholarly information on key topics and philosophers in all areas of philosophy. At present the IEP is visited by over 500,000 persons per month.

Ethics Updates is designed primarily to be used by ethics instructors and their students. It is intended to provide resources and updates on current literature, both popular and professional, that relates to ethics.

Erratic Impact's Philosophy Research Base is categorized by history, subject and author. Integrating text resources with the best online resources, this study guide attempts to aid both academic and general interest in all philosophical genres and their related fields.