Check your card
Paste your Capture Card or enter your domain. The reference checks run in your browser; nothing goes to irlpls.
or fetch it from your domain
Reads https://<domain>/.well-known/irlpls once. A browser can only do this if your server allows it (CORS).
Check a sample pack
Your browser checks the pack's signature against its stated key. Nothing else.
A sample pack is a provider's public sample file, proof and key. How to publish one
No sample packs linked.