This is beautifully done. I noticed the affiliation with investmentcalculator.io - I love that you guys are working on stuff like this. Beautiful, simple products that do one thing with a focus on UX. Make more, please!
Here's a few more live ones for your perusal:
May I ask how you generate links/publicity for these projects? https://chinesenewyear2018.com/ in particular exploded in visibility on google.
PS: Are you OK with me contacting you via mail with additional questions?