Hello, How do you know if a copywriter is really good at web development topics? What experience should he or she have in this niche? Who has come across it? Please share.
Just come out and ask them. You will be able to tell from their answer whether or not they know what they are talking about, or whether they are full of B.S.
Go to freelancing sites like odesk ,elance and many others .In thr site search for copywriters and you will see many people with reviews .If it has a lot of positive reviews then means he work for other people and they like the job and it give him positive review
If the copywriter is a successful professional, s/he will have a portfolio of past projects that you can review and decide if their work on web development topics will meet your needs. Note that portfolio's can be faked, so you will want to do a few reference checks with clients on that work.
I always try to induce people to freelancing platforms. If you have already acquainted with such ones and you understand that there are no well versed copywriters of web development topic, then try to seek for such ones of recruting paltforms, like "Indeed" for example. There are no other ways, at least, you can apply to special forums of copywriters where they discuss various peculiarities of creating content and then ask this question there. Guess that there will be some people who are ready to help you.