The best application for mastering in coding languages. Sololearn is a free app in which many programming languages can be learnt. It contains C+ , C#, Java script, python, SQL, Bootstrap, HTML, CSS and many more programming language. We can take course on any of the above and can learn every concepts in details. Besides there is code play ground in which we can test our own programs by compiling and running it.
I have done C+ programming language couse and now I am learning java script program. The complete couse is distributed in several parts. After completing each part, a short test is organised so that we can check ourselves whether we are ready to go to the next level or not. Again we can also participate in daily coding competitions. Based on our consistency and coding accuracy our xp level is increased and get promote two next tire.
It is completely free learning software to master codes. I am very grateful to this app for giving such a opportunity to learn the most needed things of modern life( programming languages) free of cost.