As mentioned, these are very competitive topics and rest assured a LOT of FAMOUS instructors already cover all the topics you've mentioned, as part of their bundled courses. You have an uphill battle to fight to get recognized. It isn't impossible to do, Andrei Neagoie managed to do it in 2017 and make a dent in the market. He did a very good course and incredible marketing through a medium blog post. My recommendation, especially if you're new to online courses, would be to create a smaller niche course of 2-3 hours on a technology you know extremely well and that is under-addressed in Udemy. If that course succeeds, and you get the rating you think you want, by all means create a larger course. Your first course is rarely the best. As far as earning potentials, make sure to check the marketplace insights tools to know how much courses are making in web dev: https://www.udemy.com/instructor/marketplace-insights/?q=Web%20Development&lang=en Top course is 50k USD per month, and the median is $18 per month. That means if you create a course in that category, unless you're really special and have all the marketing figured out, you won't succeed in making more than $100 per month. Best of luck!
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