Hi Aspirant,

Your Question is little ambiguous and difficult to fathom the exact meaning. As Per my interpretation, Some of the best sites for learning courses in Computer Science and Engineering are -

1. edX

2. Coursera

3. NPTEL

4. Stanford Engineering Everywhere

5. MIT OpenCourseWare

6. GitHub

7. W3Schools

8. Codecademy

Hope the answer helps you.

All the best.