Glad you like the idea! Obviously scaling could be an issue (20 random addresses doesn't add a lot of privacy/noise if the user inputs 5000 addresses) and there's going to be a lot of extra calls to the sochart API which could suck if they limit. I haven't looked at their API but if they give your limits in the response header I guess you could still keep it pretty quick by only adding a setTimeout when you're close to the limit?
I wonder if there's a trusted public API that lets you send a list of address instead of one address at a time? Obviously you could set one up yourself, but then you get back into the issue of sending data to your own server and thus losing trust.

I get some nice limit on sochain API.
It is a public API, free to use
Rate Limits
The public infrastructure for SoChain allows 300 requests/minute free-of-charge. Additional tiers are coming soon.
https://www.sochain.com/api#rate-limitsI looked some APIs and this was the one i liked the most for this tool.
I don't think users that need to search for 5000 address are going to use this tool.. that's way too much addresses to track!!
If bitcoindata.science goes well, There will come a time when I will need to host my own node and provide API data. But for that I need some that this domain pay for its costs, which I am far from it now.
For now, i need to work on improvements in the projects I have and to create new ones.