I used to compile my own dictionary on one Russian website. Using several dictionaries as well as surfing the internet, I made about 2,000 entries (it included both words and idioms). Unfortunately, it was then destroyed due to some glitch on the website's part, I guess. I was heartbroken and gave it up for a couple of years but I recently started to realize that my skills and lexicon have shrunken. I'm pretty sure it's because of it. You see, that custom dictionary included hand-picked sentences, and I used to regularly pronounce them aloud which helped me remember and incorporate them into my active vocabulary. I have a partial list of the words of the ruined dictionary, and I realize that I forgot some of them entirely, as if I see them for the first time. Anyway, I think it would make sense to resume my lexicographic practice and was wondering whether there's some free online service that allows you to make your own dictionary entries (like word cards but more detailed), secures them well, and has an option of downloading it for backup purposes. It also would be helpful if the website used those cards in some sort of personal games or tests that I would be offered to take to better remember the words. I don't have a smartphone so don't offer Android or iOS apps.
I'm looking for some free or freemium option.