chklinks is a non-threaded Perl link checker. It helps finding broken links on your website. It does not raises many simultaneously connections for its job, run out of the resources and crash your system in a moment.
SNARLsnmp is a web application monitor for net-snmp 5.0.3 and higher. it actively monitors performance, content, some logic and is capable to even monitor complex web transactions with highly dynamic URLs and many other features