Greasy Fork is available in English.
Allows you to download subtitles from Netflix
< Обсуждения Netflix - subtitle downloader
I don't think so. You'd probably be the only person using it. For Viki just open browser console (Ctrl + Shift + K/J depending on browser), go to Network tab and search for .vtt. Can't help with DramaFever - it wants me to install Flash and I'm not going to because it's bad. It also says "this video is currently unavailable in your country" on all videos I tested.
Viki & DramaFever Subtitle downloader
could you make a script for these websites.
I don't know what format the subtitles are in sorry.