Alert your entire team when your site goes offline.

Updown is an online service that checks your website's status by periodically sending an HTTP request to the URL of your choice. It then notifies you by email or sms when your website is not responding correctly.

Honeybadger is DevOps monitoring, for developers. *gasp!* Honeybadger simplifies your production stack by combining exception monitoring, uptime monitoring and check-in monitoring into a single, easy to use platform. ... With issue automation, Honeybadger can even create and update issues automatically as they are fixed.

Visualping is a simple service for monitoring websites for changes. You'll receive an email notification when it detects any change in the content of the page. You can either choose to monitor the whole website or just an area of a website.

StatusCake.com is a free website monitoring tool which allows users to track up to 10 websites and get alerted when their site is down or is having trouble. Downtime root cause analysis is included in the free plan to help users diagnose and fix issues.

SolarWinds Pingdom provides real user, uptime, page speed, and synthetic monitoring of web applications from outside the firewall. Pingdom is part of the full-stack SolarWinds APM Suite, including AppOptics and Loggly.

Bugsnag is an error-monitoring tool that allows your developers to identify, prioritize and replicate bugs in a time-efficient and enjoyable manner. Bugsnag creates an ownership mentality with all developers by enabling them to proactively see the effects of their code. This helps them address issues before these escalate, creating a joyful experience for both customers and engineers.

StatusGator aggregates the status of all the cloud services, hosted applications, and websites you use into a single status page for your team.