The limits are ok imo
https://mempool.space/pt/docs/api/rest
Mempool.space API is actually just an Esplora instance, so I realized that I already have a client developed to access the Esplora API.
It's the same API that blockstream.info uses - that one has no rate limits, but I couldn't find any information about mempool.space's customized rate limits for anonymous usage - Do you happen to know about these limits by any chance?
I have hit the a few times using this tool:
https://bitcoindata.science/bitcoin-balance-check.html
Each address will make one request, and as they are nearly simultaneous you get the limit if you add many addresses (like dozens).
But you won`t get blocked, you will just receive a 429 error (too many requests). and it works again a few seconds later.
I just hit it now after 40+ requests in a minute