Similar services myefe.ru for collecting English words (dictionary) are there?

Question

English learning tools

I use this service, there is a limit of 2000 words. I bought a subscription for 50 rubles a month, in principle, not expensive. But it works online because of this brake, is there really no similar program. Or free online can eat?

1. adding words with deleting duplicates
2. Add sentences and then extract the words and compare them to duplicates like in this site

I would write it myself on a PC or android, only it’s a pity that no one has done it how much I’m looking for, I can’t find it.