I have been working in the IT industry and i must say that there are currently many great encryption solutions out there. If you're looking for one that is already big in the market, then i suggest VeraCrypt. Veracrypt has been one that i've been using since truecrypt and my college years.
But if you want a password-less encryption app/computer program, then i suggest Cloakapps. High-level encryption is used so you don't have to worry about anything else. I haven't used Veracrypt ever since i discovered Cloakapps and and that has been almost a year ago.
I am a professional working in the financial sector, dealing with spreadsheets of sorts (balance/legal). Looking for file encryption solution that works across multiple platforms (in terms of OS and PC/mobile) so that my clients may have it too and possibly free? Simple to use as well. Your help is massively appreciated!