Read a list of domains (e.g. from subfinder) and check whether they resolve to successful HTTP responses

subchecker.sh

#!/bin/bash

# Example:
# subfinder -d wakapi.dev | subchecker.sh

while read -r domain; do
    if curl -s -o /dev/null -w "%{http_code}" "https://$domain" | grep -q "^2"; then
        echo "https://$domain: OK"
    else
        echo "$domain: FAILED"
    fi
done