Two bad things about preev: no TLS and it tries to load Google trackers.

I like how fast btc2fiat.me loads and that it has no trackers.
One improvement / addition suggestion, would be a completely static version, that lets you pass a URL parameter.
It would be even more lightweight and require no JavaScript.
Let's say I go to
https://btc2fiat.me/?btc=0.5, it would display a static version of the current webpage, with the amount set to 0.5BTC.
And
https://btc2fiat.me/?usd=50.0 would display the exchange rate for 50USD.
My motivation for this idea is:
https://plaintextsports.com/