Successful people have one common trait: they never stop learning. If you are always looking to expand your knowledge or skills, these self-study apps and sites have plenty of material for life-long learners.

There are several things not taught in school that you still need to know as you grow. The internet has made it easier to share knowledge for free with online courses, videos, articles, podcasts, and apps. The websites in this article point you towards paths and resources to learn anything you want without spending a penny.

1. Learn Awesome (Web): Knowledge Base for Varied Online Learning Resources

Learn Awesome suggests how to learn any subject based on online materials like podcasts, books, forums, courses, flash cards, summaries, videos and films

Learn Awesome is trying to become for online learning what Wikipedia is for online knowledge. It calls itself a "learning map" for people to find different resources and recommendations on the internet to learn about something.

Importantly, the focus isn't just on finding the best online courses and MOOCs. Learn Awesome acknowledges that different people learn differently, and knowledge is available in different mediums. This website will collect them all in one place, and you choose how you want to learn.

For example, if you pick history as the topic, Learn Awesome will tell you the best history teachers across podcasts, books, forums, chat groups, MOOCs, flashcards, dedicated Q&A boards, summaries and notes, videos and films. Some of the tile cards contain short descriptions, but mostly you'll need to go to the creator's own page to find out more.

One can browse Learn Awesome by topic, experts, users, or format. In formats, you'll find the different types of resources if you filter based on your learning style (like only listening to podcasts). The website isn't as comprehensive as Wikipedia yet, but it has all the ingredients to become a knowledge base for self-learning online.

2. CosmoLearning (Web): Oldest Curator of Self-Learning Videos and Courses

CosmoLearning has been curating the best resources to learn anything online since 2007

Since 2007, CosmoLearning has been collecting the best free educational videos online and turning them into unique learning paths. As one of the oldest curators of online education, it has developed a reliable and informative knowledge base.

Browse the site by subject till you find a topic you like. Then, you can read a summary about it and check for material related to it like courses, documentaries, videos, and images—all sourced from reliable places like universities and experts. The contributors at CosmoLearning also add other valuable information like articles and books related to a topic.

On the main page, CosmoLearning displays the most popular documentaries, courses, videos, and books, in case you can't decide what you want to learn about. Registering for the site will let you also contribute materials and talk with fellow self-study enthusiasts. Learning is always more fun as a group.

3. Trickle (Web): Learn Complex Topics in Short Daily Lessons

Trickle delivers daily short lessons so you can learn complex subjects in microbursts

Trickle teaches complex subjects by breaking them down into small lessons sent to you daily. It's a concept called drip learning, where you learn new things in short and fun ways and thus make learning a part of your daily routine rather than a dedicated activity.

Register for Trickle and choose a topic or "stream" that you're interested in. You'll discover several streams already curated by experts and users. Each stream is made up of several lessons, each approximately worth 5-10 minutes of reading time. You'll get one new lesson every day to learn and absorb, but you're free to choose to read more than one drip at a time.

Within the lesson, you'll find tags that you can tap to learn more about a concept or person, or find which other lessons they're tagged in. Lessons also have highlights at the end. You can add a private note in each lesson or a public comment. You can add drips to your own stream to create or curate topics for your learning.

4. Open Masters (Web) and Informal PhD (Ebook): Self Study Guides and Communities

Open Masters gives you tools and support to chart your own learning path for self-education

You don't need to adhere to the academic curriculum laid out by universities for higher education. If you truly want to learn something, you can make your own learning path. Two movements, Open Masters and Informal PhD, teach you how to do that.

Open Masters is a community of lifelong learners who are eschewing traditional education in favor of charting their own studies. You'll find helpful resources like the Wayfinder's Mandala to gain clarity on what you should learn, and step-by-step articles on how to go about it.

Informal PhD is a free ebook by author and TEDx Speaker Alex Bretas on his journey of an informal education. You can get a short idea of it through his Medium post, but if you truly want to learn how to make your own learning path, you'll want to read the full book.

Download: Informal PhD by Alex Bretas (PDF | Free)

5. Learning Sabbatical (Web): How to Plan and Follow Through on a Learning Journey

Learning Sabbatical tells you how to take a break from work to plan and follow through on an education to grow your skills

You need to pick up new skills as you progress, but it can be difficult to juggle that along with a full-time job and other personal responsibilities. A new trend among working professionals is to take a "Learning Sabbatical" to grow as a person.

It sounds daunting to miss work for "just some course," but it's better than burning the candle at both ends. If you truly want to grow your skills, you need to give yourself the time and opportunity to imbibe what you learn, rather than just have a certificate saying you're qualified. The Learning Sabbatical website guides you to do just that.

You will find out how to plan your learning sabbatical through a process that clarifies what your target is and how you will achieve it. It also pushes meta-learning resources, i.e., finding out how to learn efficiently. Most of the advice comes from the site author Chris's personal experiences on his learning journey. You can also read a few profiles of people who have taken learning sabbaticals and what they discovered along the way.

Explore New Platforms and Find Buddies

Whether you learn in daily drips or take a full-time course, the one thing you shouldn't do is stop in your quest for more knowledge. The internet has made it possible for anyone to get a free education that is valuable and helps you grow. It's all about knowing where to look.

For example, two previously mentioned apps are fantastic for lifelong learners to find study partners and different courses. Prodeus is a Chrome extension that catalogs courses and in-depth tutorials on YouTube, which are notoriously difficult to find in one place. And Cuddy will help you locate a study partner to take classes online and compare notes.

Of course, there must be several other such unique platforms and communities; it's all about finding those that motivate you to keep learning and growing.