Tom's Learning Notes

The Protagoras is a Socratic dialogue which features perhaps one of the most interesting of Socrates' intellectual opponents. Plato provides a relatively sympathetic portrait of the sophist Protagoras, a historical figure who is believed to have been close to the Athenian leader, Pericles. 

Free Online and Downloadable Texts

About.com: Protagoras Dialogue - Benjamin Jowett Public Domain Translation.

Gutenberg: Protagoras by Plato, translated by Benjamin Jowett, multiple formats.

Loebulus. L165 - Plato - Laches. Protagoras. Meno. Euthydemus. PDF of public domain Loeb edition in Greek and English.

Perseus: English text (Lamb, 1967). Greek text (Burnet, ed 1903). 

University of Adelaide (Internet Archive): Protagoras, translated by Benjamin Jowett. EPUB, HTML and MOBI formats.

Wikisource: Protagoras, translated by Benjamin Jowett.

Other Resources

Approaching Plato: A Guide to the Early and Middle Dialogues

Internet Encyclopedia of Philosophy: Protagoras - biography of the historical sophist.

PhilPapers: Plato - Protagoras - bibliography with open access option.

Librivox: Protagoras - audiobook.

Wikipedia: Protagoras

The Great Conversation: Further reading at Tom's Learning Notes

Ancient Greek resources: learn to read Greek classics in the original.

Bloom's Western Canon: Plato's Dialogues are listed.