A number of translations of Plato's Symposiumk are available for free online, These will typically be older translations, long since passed into the public domain, which is why they are free.

• Plato's Symposium, Jowett translation (Internet Archive)
• Plato's Symposium, Jowett translation (Project Gutenberg)
• Plato's Symposium, Jowett translation (Wikisource)
  
• Plato's Symposium, Fowler translation (Perseus)
• Plato's Symposium, Horrian translation (Foundation For Platonic Studies)
  

You can find a free audio version of the text at Librivox

• Plato's Symposium, Jowett translation (Librivox)

You can find the Greek original of the text as well at Persius

• Plato's Symposium (Persius)