Personally, I have come to realize that you cannot truly prepare for a technical interview no matter what you do. You can study for months in a futile attempt to commit to memory everything that might be relevant (data structures, algorithms, maths, statistics, API reference etc.) but they will always find something to ask you that you missed during your studies.
These days I simply reply that I do not do technical interviews any more as I do not believe these can efficiently probe one's professional abilities and I cannot justify expending time in memorizing bulkloads of trivial information for the sake of going through some rite of passage, which some interviews often turn into.
Agreeing to a technical interview also puts you at a disadvantage. They will probe your weak spots and then use this knowledge to publicly disgrace you, declare you less competent than what you'd like them to believe and then to low-ball you with an offer below what you might otherwise get. Many developers fall for that trick, the best you can do is to make sure you don't join their group.
Just say to them you will not do a technical interview (or a test project on your own unpaid time) but that you are prepared to meet and have a constructive discussion around their needs and your willingness to possibly help them out with whatever they have in mind. If they don't like it, skip them for the next company in your list.
These days I simply reply that I do not do technical interviews any more as I do not believe these can efficiently probe one's professional abilities and I cannot justify expending time in memorizing bulkloads of trivial information for the sake of going through some rite of passage, which some interviews often turn into.
Agreeing to a technical interview also puts you at a disadvantage. They will probe your weak spots and then use this knowledge to publicly disgrace you, declare you less competent than what you'd like them to believe and then to low-ball you with an offer below what you might otherwise get. Many developers fall for that trick, the best you can do is to make sure you don't join their group.
Just say to them you will not do a technical interview (or a test project on your own unpaid time) but that you are prepared to meet and have a constructive discussion around their needs and your willingness to possibly help them out with whatever they have in mind. If they don't like it, skip them for the next company in your list.