The best lists I know of are on Wikipedia, they cover more subtleties than just "visa-free" but they are unfortunately not 100% complete probably because 300 some citizenships multiples by 300 some countries to visit would result in 90,000 entries to get right and maintain.
Sometimes you don't need a visa at all, sometimes you don't need a visa but you need something else (eta for Australia, esta for USA). Sometimes these are very restricted, such as one or two days and only if you enter at certain airports.
For instance I'm an Australian citizen with only an Australian passport so I can consult this Wikipedia article:
Visa requirements for Australian citizens
From your Stack Exchange profile I'm going to assume that you travel on a Belgian passport so your Wikipedia article is:
Visa requirements for Belgian citizens
Though it's not complete it's a wiki so when you go to the trouble to find out some information for your needs that's not yet included, you can edit the article and add the information as a way to thank Wikipedia and help everybody else that looks there when they're in a similar situation to yours.