Handy Free Tools for Learning Mandarin Online
FastChinese.org is a free, mobile-friendly website with several useful tools for Chinese learners.
The free resources include access to Mandarin flashcards with auto-adaption to your learning speed, a Chinese dictionary allowing multiple forms of search (Hanzi characters, Pinyin and English) and a speaking tutor. There's also a concise beginner's introduction to learning the Chinese language.
You'll need the Google Chrome browser to access all the features enabled via additional free apps.