What are reliable sources to download plain-text files listing current composition of various popular indexes such as S&P 500 (SPX) or Dow Jones Industrials (DJI) or Nasdaq 100 (NDX) ?
At a minimum the file would include symbol, but hopefully name, sector, and other information.
The ideal format would be JSON , but XML or XLSX, but even simple formats such CSV or one symbol per line would be acceptable.
I've checked provider websites such as :
but no luck yet.