diff --git a/free-programming-books.md b/free-programming-books.md
index ccf0e78f57c97dbff220d824ed8119924ed50ecd..10d0b1a6657780adf8af1166a831dca548a1c10f 100644
--- a/free-programming-books.md
+++ b/free-programming-books.md
@@ -1656,7 +1656,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [JavaScript for Impatient Programmers (ES2020 edition)](https://exploringjs.com/impatient-js) - Dr. Axel Rauschmayer
 * [JavaScript Fundamentals, Plus a Dash Of JQuery - for dinner ladies](http://nicholasjohnson.com/javascript-book/)
 * [JavaScript Garden](http://bonsaiden.github.io/JavaScript-Garden/) (Maintained by Tim Ruffles)
-* [JavaScript Notes for Professionals](https://goalkicker.com/JavaScriptBook/) - Compiled from StackOverflow documentation (PDF) 
+* [JavaScript Notes for Professionals](https://goalkicker.com/JavaScriptBook/) - Compiled from StackOverflow documentation (PDF)
 * [JavaScript Patterns Collection](http://shichuan.github.io/javascript-patterns/) - Shi Chuan
 * [JavaScript Spessore](https://web.archive.org/web/20160325064800/https://leanpub.com/javascript-spessore/read) - Reginald Braithwaite
 * [JavaScript Succinctly, Syncfusion](https://www.syncfusion.com/resources/techportal/ebooks/javascript) (PDF, Kindle) (email address *requested*, not required)
@@ -1694,7 +1694,7 @@ Kerridge (PDF) (email address *requested*, not required)
 * [AngularJS Notes for Professionals](https://books.goalkicker.com/AngularJSBook) (PDF)
 * [AngularJS Succinctly](https://www.syncfusion.com/resources/techportal/ebooks/angularjs) (PDF, Kindle) (email address *requested*, not required)
 * [AngularJs vs EmberJs](http://angularjs-emberjs-compare.bguiz.com)
-* [Build a Full-Stack Web Application Using Angular & Firebase](https://www.c-sharpcorner.com/ebooks/build-a-full-stack-web-application-using-angular-and-firebase) - Ankit Sharma 
+* [Build a Full-Stack Web Application Using Angular & Firebase](https://www.c-sharpcorner.com/ebooks/build-a-full-stack-web-application-using-angular-and-firebase) - Ankit Sharma
 * [Practical Angular: Build your first web apps with Angular 8](https://leanpub.com/practical-angular) - Ahmed Bouchefra *(Leanpub account or valid email requested)*
 * [Seven-Part Introduction to Angular](http://ngokevin.com/blog/angular-1/)
 * [Unit Testing Best Practices in AngularJS](http://andyshora.com/unit-testing-best-practices-angularjs.html)
diff --git a/free-programming-playgrounds.md b/free-programming-playgrounds.md
index 39bd832a373cde34fe33ad5f00d6e61d94b8d59c..c7b0014e29cc887f65c2c714283dd2371f8db1f2 100644
--- a/free-programming-playgrounds.md
+++ b/free-programming-playgrounds.md
@@ -126,6 +126,7 @@
 ### Kotlin
 
 * [Kotlin](https://play.kotlinlang.org)
+* [Kotlin Playground](https://developer.android.com/training/kotlinplayground)
 
 
 ### Kubernetes