Brokenlink.io

Brokenlink is an automated broken link checker that monitors every URL you care about around the clock and alerts you by email or Slack the moment one dies — so a broken link never sits unnoticed for days, weeks, or months. A free one-off link checker only tells you about today. Brokenlink re-checks continuously, tracks each link's status history, and reports the exact URL and status code the moment something breaks. Set it up once and never check a link by hand again.