Stack Exchange is a site where people can ask questions to the community and get answers back. These answers are then rated by other people in the community and the most helpful answer can be chose... Read more.

chinese.stackexchange.com

This site contains a huge number of lessons, complete with texts, vocabulary, audio, exercises and much more. And it's all free. Note that if you want to get the intermediate and advanced material,... Read more.

collections.uiowa.edu

Mandarin Chinese With Fiona Tian is a free video resource for learning Mandarin Chinese in a fun, enjoyable way. Chinese doesn't have to be hard. Kick back, relax, and enjoy. Read more.

mandarinmadeez.com

Finally, Duolingo added a En->ZH course. As Duolingo is the most popular gamification learning app, the learning experience is relatively streamlined and tested. The monetarization aspect leads to ... Read more.

en.duolingo.com

Langademy is a language learning social network that connects students with natives from all over the world. Students can practice Chinese, English, French or any other language at Langademy by mak... Read more.

langademy.com

This site is a free resource for beginner learners of Mandarin who are looking to develop basic conversational ability for social, travel or work situations. It currently contains a small archive o... Read more.

mandarinhq.com

This site offers language exchange partners (and also seems to plan to provide tutors and language teaching services as well). The language partner part of the site is free, though, so if you're lo... Read more.

liveitchina.com

ChineseForUs offers a large number of free videos on YouTube. The most basic lessons are much like other lessons found on YouTube, but if you skip to HSK 2 or so, there’s a surprising amount of Chi... Read more.

youtube.com

看剧学汉语 is a community on Discord, gathering more than a thousand members, both native speakers and learners. While 看剧 (as in "watch TV series) is part of the name, the server also covers lots of oth... Read more.

discord.gg

ChineseMe is the most integrated Mandarin course, designed for motivated learners who have decided to become fluent. It is an interactive textbook that adapts itself to your interests. The course i... Read more.

chinese-me.com

Get Online Mandarin Chinese lessons from our Personal Language Tutors through Skype to increase your opportunities for career, travel and friendship or to follow your favourite Chinese film. Read more.

nativemonks.com

This is a character-by-character beginner course in Chinese, provided free of charge at the Open Languages Project. It teaches you to read (and listen to) Chinese by explaining and introducing one ... Read more.

oplang.org

Foreigncy has nearly 300 free Mandarin language training sets that help improve your media vocabulary, reading comprehension, and listening skills while raising your awareness of regional events. T... Read more.

foreigncy.us

From their website (if you have personal experience of their courses, please leave a comment): New Concept Mandarin specializes in teaching Mandarin Chinese (Putonghua) as a second language. Act... Read more.

newconceptmandarin.com