Chris Hsu translated the dopdf.com website in Chinese Traditional. If you are a Chinese speaker you can check out the newly translated version here: dopdf.com/tw/. 謝謝 Chris! (hopefully this really means Thank you in Chinese).
If you want to help us translate the website (or the interface) in a language that's not yet translated in, you can start by visiting this page: Languages. You'll see here in which languages doPDF is not translated, and if you want to help you'll simply have to email us and we'll reply with details. Practically the website has about around 1200 words that need to be translated.