DeadLinkPatrol

DeadLinkPatrol crawls every page of your websites on a schedule, checks every internal and external link, image and script, and alerts you by email or HMAC-signed webhook only when new breakage appears, with the exact page to fix. Agencies monitor up to 50 client sites daily and share white-label link-health reports. Every account has an API key, and there's a free WordPress plugin that shows results in wp-admin with no server load. Plans: Free (1 site), Starter $9/mo (3 sites, weekly), Agency $79/mo (50 sites, daily).