diff --git a/courses/free-courses-en.md b/courses/free-courses-en.md
index bed5398d0..c90df67be 100644
--- a/courses/free-courses-en.md
+++ b/courses/free-courses-en.md
@@ -114,8 +114,8 @@
 * [Princeton University Algorithms, Part 1](https://www.coursera.org/learn/algorithms-part1)
 * [Princeton University Algorithms, Part 2](https://www.coursera.org/learn/algorithms-part2)
 * [Sorting Algorithms](https://www.youtube.com/playlist?list=PL2_aWCzGMAwKedT2KfDMB9YA5DgASZb3U) - mycodeschool
-* [Stanford University Algorithms: Design and Analysis, Part 1](http://online.stanford.edu/course/algorithms-design-and-analysis-part-1)
-* [Stanford University Algorithms: Design and Analysis, Part 2](http://online.stanford.edu/course/algorithms-design-and-analysis-part-2)
+* [Stanford University Algorithms: Design and Analysis, Part 1](https://online.stanford.edu/courses/soe-ycsalgorithms1-algorithms-design-and-analysis-part-1)
+* [Stanford University Algorithms: Design and Analysis, Part 2](https://online.stanford.edu/courses/soe-ycs0001-algorithms-design-and-analysis-part-2)
 * [This is CS50x](https://cs50.harvard.edu/x/2021) - David J. Malan (Harvard OpenCourseWare)
 
 
@@ -402,7 +402,7 @@
 * [Build a Personal Website with Dash](https://dash.generalassemb.ly)
 * [Build a responsive website with Webflow](https://www.bloc.io/tutorials/webflow-tutorial-design-responsive-sites-with-webflow)
 * [Build a SaaS landing page using Skeleton](https://www.bloc.io/tutorials/jottly-a-beginner-s-guide-to-html-css-skeleton-and-animate-css)
-* [Build Dynamic Websites](http://cs75.tv/2010/fall/)
+* [Build Dynamic Websites](https://web.archive.org/web/20210812200413/http://cs75.tv/2010/fall/) - David J. Malan [(YouTube)](https://www.youtube.com/playlist?list=PLvJoKWRPIu8GhAhDBAH0BFB9BS7YxM1WT)
 * [Code Your First Game: Arcade Classic in JavaScript on Canvas](https://www.udemy.com/code-your-first-game/) - Chris DeLeon (Udemy)
 * [Complete HTML/CSS BootCamp](https://frontendmasters.com/bootcamp/) - FrontEnd Masters
 * [Conquering freeCodeCamp's Curriculum](https://youtube.com/playlist?list=PLgBH1CvjOA62oNEVgz-dECiCZCE_Q3ZFH) - Florin Pop (Youtube)
@@ -441,7 +441,7 @@
 
 ### Java
 
-* [Advanced Software Construction in Java](https://www.edx.org/course/advanced-software-construction-java-mitx-6-005-2x#!)
+* [Advanced Software Construction in Java](https://openlearninglibrary.mit.edu/courses/course-v1:MITx+6.005.2x+1T2017/about)
 * [Central Connecticut State University, Introduction to CS Using Java](http://chortle.ccsu.edu/CS151/cs151java.html)
 * [CS106A - Programming Methodology](https://see.stanford.edu/Course/CS106A) - (Stanford)
 * [Introduction to Java](http://ocw.mit.edu/courses/electrical-engineering-and-computer-science/6-092-introduction-to-programming-in-java-january-iap-2010/)
@@ -461,7 +461,7 @@
 * [Princeton Algorithms, Part 1](https://www.coursera.org/course/algs4partI)
 * [Problem Solving With Java](https://www.udacity.com/course/intro-to-java-programming--cs046) (Udacity)
 * [Programming in Java](https://nptel.ac.in/courses/106/105/106105191/) - Prof. Debasis Samanta (NPTEL)
-* [Software Construction in Java](https://www.edx.org/course/software-construction-java-mitx-6-005-1x)
+* [Software Construction in Java](https://openlearninglibrary.mit.edu/courses/course-v1:MITx+6.005.1x+3T2016/about)
 * [Spring 5 Core - An Ultimate Guide](https://www.udemy.com/learn-spring-5-core-from-scratch/) - Somnath Musib (Udemy)
 
 
@@ -487,7 +487,7 @@
 * [Learn JavaScript - Full Course for Beginners](https://www.youtube.com/watch?v=PkZNo7MFNFg) -  Beau Carnes, freeCodeCamp.org (YouTube)
 * [Learn modern JavaScript](https://scrimba.com/learn/es6) - Beau Carnes (Scrimba) (Scrimba account *required*)
 * [Learn to Program in Javascript: Beginner to Pro](https://www.udemy.com/course/programming-in-javascript) - Raghavendra Dixit (Udemy)
-* [learn:query](https://learnquery.infinum.co)
+* [learn:query](https://learnquery.infinum.com)
 * [Namaste 🙏 JavaScript: An In-Depth JavaScript Fundamentals Course](https://www.youtube.com/playlist?list=PLlasXeu85E9cQ32gLCvAvr9vNaUccPVNP) - Akshay Saini (YouTube)
 * [npm - Mastering the Basics](https://www.udemy.com/course/npm-mastering-the-basics/) - Vishwas Gopinath (Udemy)
 * [Object-Oriented JavaScript](https://www.udacity.com/course/object-oriented-javascript--ud711) - Richard Kalehoff (Udacity)
@@ -566,7 +566,7 @@
 
 #### Redux
 
-* [Getting Started with Redux](https://egghead.io/series/getting-started-with-redux)
+* [Getting Started with Redux](https://egghead.io/courses/fundamentals-of-redux-course-from-dan-abramov-bd5cc867)
 * [Learn Redux](https://learnredux.com) - Wes Bos (email address *requested*)
 
 
@@ -618,7 +618,7 @@
 ### Lua
 
 * [Learn Lua in 15 Minutes](http://tylerneylon.com/a/learn-lua/) - Tyler Neylon (HTML)
-* [Lua Interactive Crash Course](http://luatut.com/crash_course.html)
+* [Lua Interactive Crash Course](https://web.archive.org/web/20201111225216/luatut.com/crash_course.html)
 * [Lua Tutorial](http://www.tutorialspoint.com/lua/)