Best of all, many high quality  sites are completely free. From history to coding, excellent free  education awaits on the following 25 sites.
 
Coursera.org is a website  that partners with universities and organizations around the world. This  brings a wide variety of topics and perspectives to one searchable  database. Coursera is a powerful tool for free online education, and  includes courses from many top universities, museums and trusts. This  gives the site an extremely wide range of in-depth courses. Coursera is  extremely useful if you’re looking to study many different topics, or  want courses from different schools and groups.
Partnering with many post secondary schools, Khan Academy offers a  useable, well organized interface. Also curating many courses from  around the web, Khan Academy offers impressive depth on many different  subjects. Among the more well known educational sites, Khan Academy is  also incredibly useable, which may make it easier to keep learning  goals.
If you are struggling to find exactly the material you are looking  for, try Open Culture’s listing of free online education courses. The  page highlights 1000 lectures, videos and podcasts from universities  around the world. The site features a lot of material found only on  universities private sites, all in easy to browse categories. This means  you can find hundreds of university courses, without having to visit  and search each university’s own site. Open Culture’s list features  courses from England, Australia, Wales and many state universities  around the United States. A very helpful resource for finding many  courses in one area of study.
Udemy’s free courses are similar in  concept to Coursera’s but additionally allows users to build custom  courses from lessons. Working with many top professors and schools, the  site mixes the customizable platform of other sites with a heavy  emphasis on top quality content. This is another site however, that  mixes free and paid content.
Another site with courses from many different schools is Academic  Earth. Much like the three sites above, Academic Earth brings together  top notch courses from many different sources, and focuses on offering a  wide variety of subjects. Academic Earth lists courses by subject and  school, so it might be easier to find what you’re looking for.
Another great option for free online education is edX. Also bringing  together courses from many different schools, the site has impressive,  quality information for everyone. edX covers a great range of topics.
Unlike the previous sites on this lists, Alison is a free education  site offering certification in some areas. Alison offers courses mainly  in business, technology, and health, but also includes language learning  courses. A great option if users need certification for their learning,  Alison also offers school curriculum courses.

A very convenient place for free online  education is iTunesU, because it integrates seamlessly with your iPod,  or any app-ready Apple mobile device. On iPad, iPhone, or iPod touch,  users download the iTunesU app. Desktop users can access  iTunesU on the  upper right hand corner of the iTunes Store. iTunesU is also convenient  because the store is categorized much like iTunes. Users can search  learning materials in many different ways, including genre and topic.  However, courses are often a mix of free podcasts or videos, and paid  content. ITunesU does include courses on a pretty wide scope of topics,  but does not integrate with Android, Google or Windows mobile devices.

Your hub for all the online offerings from Stanford University,  Stanford Online offers self-paced and session based courses. While  Coursera features some courses from Stanford, many classes are only  available via other hosts. Some courses require iTunes, but most are  completed in your web browser. Stanford Online is a great site for high  quality courses, though the topics are somewhat limited compared to  sites partnered with more than one school.
Like Stanford Online, Harvard Extension features free online  education courses from Harvard only. This is another excellent source  for top notch course material, though the course variety is less rich  than multi-school sites. Additionally, Harvard Extension allows you to  search for courses by professional certificate. This makes it much  easier if your online education goal includes certification.
Open Yale Courses echoes Harvard Extension and Stanford Online, in  that it offers only courses from Yale. While the site is similarly  limited to topics taught at the school, Open Yale Courses offers a lot  of videos of actual campus lectures. The availability of videos makes  the site a great option if you’re looking for quality courses, but learn  better by watching than by reading.
Much like the other schools on this list,  UC Berkeley has a variety of free online education options. The school  has slightly fewer courses than the schools above, but includes some  supplementary lectures, webcasts and RSS Feeds, making it easy to keep  up with the topics you choose.
Similarly, MIT offers a variety of free  courses. The school has a comparable number of courses to the schools  above, plus includes very in-depth course materials on the subjects  available. MIT also offers free RSS feeds, a convenient way to continue  learning.
Carnegie Mellon’s free online education  site is comparable with the other school’s on this list, however, Open  Learning Initiative also covers a smaller range of topics. But for the  topics that are covered impressive, in-depth material is available.
Codecademy is a website dedicated specifically to teaching coding.  Where other coding sites follow an example/practice session workflow,  Codecademy includes a live practice window. This means you can practice  coding while still viewing the lesson material. The courses at  Codecademy are well written and easy to follow and the website is  organized very nicely. Codecademy features a centralized dashboard where  you can monitor your progress, plus organizes lessons into complete  modules. This lets you learn an entire language without needing to pick  the next course manually.

Code is another website focused on coding and app writing. A site  with high quality courses, Code also features learning options for kids.  In addition to kid friendly courses, Code offers free online education  classes on a wide variety of technology topics. These classes include  app writing, robotics and Javascript. Most of the courses are also  geared in a such a way that they can be useful in a classroom setting.  This makes Code a great resource for harder to find coding topics, as  well as various learning settings.
The podcast page on the University of London website is another great  source for free education. While the courses are limited to podcasts,  the site features podcasts from it’s own campus, as well as eleven  universities in and around London. This gives learners a wide base of  topics and lectures, but still ensures in-depth material.
Similar to the University of  London, the University of Oxford features many different podcasts. Most  are public lecture series or lectures from visiting professors, with  several different recordings available. The advantage to this particular  site is that podcasts are organized into series, making it easy to  subscribe to multiple lectures on one topic. Another good site for  thoroughly in-depth lectures.
For the more casual learner, the BBC offers a wide variety of  podcasts on many different topics. Most podcasts are updated weekly, and  focus on everything from finance, to sports, to current events. Through  the World Service line of podcasts, there are also many in different  languages. The focus of these podcasts are less in-depth and theory  based, which may be more accessible to the average person.
Another great destination for more  general learning is TED-Ed. From the same people that brought you the  all encompassing, motivational web series, comes a site chocked full of  educational videos. Most include impressive animation, and all are ten  minutes long or less. Not only is TED-Ed an excellent site for the  curious, it also includes supplemental materials and quizzes on the  videos. This makes the site extremely useful in formal education  settings, as well as in entertaining ways to brush up on new discoveries  and topics.
LessonPaths is another great tool for  those looking for a more usable and convenient way to access learning  material. On this site, users create link playlists of their favorite  learning materials from other sites. Users then rank these collections,  making it easy to find many different high quality, accessible sources  on a given topic.
Another impressive free online education  site offering ease of use and convenience is Memrise. Available both on  desktop and as an app, Memrise is a particularly powerful tool if you  are studying a language. The site encompasses many other topics as well,  though some of the course material is user generated content. Part of  what makes Memrise speacial is their integration of games into the  learning materials, mixing learning with entertainment.
The kids site for National Geographic is  another site that makes free online education applicable for younger  users. For those looking for kid friendly education, a large variety of  games, puzzles, videos and photos keeps kids interested on this site.  National Geographic Kids doesn’t organize learning into courses, making  materials available by topic and medium instead. This makes National  Geographic Kids a good option for those looking for a more casual  learning environment.
Fun Brain is another good option for kids  who want to learn online, but focuses on games and fun puzzles.  Particularly focused on math and reading, Fun Brain’s game based  approach can be valuable if the child in question struggles to pay  attention. Fun Brain offers rewards and challenges as well, and is  another site aimed at a casual learning experience for kids K-8.
Similar to the sites for kids free online  education is Whyville a destination for preteen online learning. The  site includes a variety of social features, with a focus on learning  materials geared for young teens. Whyville also mixes in educational  games, to make the site a well rounded option for kids too old for  simple games, but too young for heavy reading based material.