Let’s Monitor offers free monitors for SSL Certificate Validity at letsmonitor.org and has simple pricing for other types of monitors:

Upgrading unlocks advanced monitor types, and allows for unlimited SMS messages.


Monitor Types

The following monitor types are available

  Website

The website monitor uses our global network of monitoring stations to make sure your website is available and responsive from around the world. The website monitor continuously checks your site for the following issues:

  • If the site is up or down
  • If the site loads within a time that you set
  • If DNS is responding
  • If content on the site matches what you expect (see the ‘match phrase’ item)
  • How long it takes to resolve DNS, connect to the site and download the HTML
  • For secure sites, whether the certificate is matches the domain
  • For secure sites, whether the certificate is expired
  • For secure sites, whether the certificate is valid
  • If the URL redirects, that the target exists

  Certificate Validity

The certificate monitor is used to check validity of certificates and alert you prior to your certificates expiring:

  • Whether the certificate is accessible
  • Whether the certificate is matches the domain
  • Whether the certificate is expired
  • Whether the certificate is valid
  • Whether the certificate has a revoked root CA
  • Whether the certificate supports a cipher that has been deprecated

  Google Safe Browsing

The Google Safe Browsing monitor checks if your site has been flagged by the Google Safe Browsing service for hosting malware or being a phishing site.

Google provides this service in order to warn users to websites that the site is unsafe. It is also used by security systems to prevent users from browsing listed sites.

If you are listed, it is an indication that your site has been compromised and/or infected with malware.

  Domain Blocklist

This monitor checks if your domain has been blocklisted, using the most reputable blocklists. This can occur if a certain threshold of complaints are received by the listing services. Website domains can be blocklisted by appearing on emails that are considered spam.

However, you do not actually need to be engaged in spam to get listed. Domains are listed based on algorithms that can trap non-spammers unknowingly.

The effect of being blocklisted is that most of your emails will no longer be delivered.

  Email Blocklist

This monitor checks if your email server’s I.P. address has been blocklisted, using the most reputable blocklists. This can occur if your email server is misconfigured (as an open relay), compromised or is sending spam.

Like domain blocklists, you do not actually need to be engaged in spam to get listed. Email servers can be blocklisted due to hacks, or in some cases, because the server’s I.P. address is close to a spam sending email server’s I.P. address.

The effect of being blocklisted is that most of the email transmitted by your server will not be delivered. Generally, the emails are simply dumped – not routed or delivered.

  DNS Expected Values

The DNS monitor uses our global network of monitoring stations to make sure your DNS values have not changed. You can set up specific checks at specific stations in the case of regional differences in DNS record values.

The DNS monitor supports checking all common DNS record types. You add a record type and expected value, and if that changes you will alerted. This protects against malicious or accidental changes.

You can populate the expected values with your existing DNS values by clicking on the ‘Get Existing Values’ button.

  Botnet/Malicious User Detection

This monitors suspicious or fraudulent users and alerts you when the user quality score drops below a threshold. This is enabled by placing a JavaScript snippet on your pages.

We score each user on your website based on algorithms that detect the likelyhood that a user is a bot. To see how we score users, click here.

User quality is scored as a number from 0-1000. Lower is worse. Quality scores are catergorized as follows:

Score RangeCategory
0 to 99Invalid – there is nearly a certainty that these users are not valid. Being in this category indicates that the user failed a determinitive test on validity. The strongest policies should be put in place for these users.
100 to 200Low Quality – The users failed one or more non-determinitive checks.
200 to 500No major issues found with the users, but it is possible minor issues were found.
500 to 1000In the future, we will be implementing whitelisting checks for users. If a user passes a whitelist check, they will score above 500.

Once implemented, there is sophisticated reporting available on the types and origins of the malicious users and bots.

  Real User Performance

Monitors global load times and satisfaction levels from real users. Find issues based on real user experiences. Optimize your site’s performance based on dozens of attributes including location and device. This is enabled by placing a JavaScript snippet on your pages.

We monitor the following metrics for issues:

DNS TimeThe average amount of time DNS resolution takes.
Response TimeThe average amount of time the webserver takes to begin the response to the user.
Interactive TimeThe average amount of time in milliseconds before the page becomes interactive.

Once implemented, there is sophisticated reporting available on performance issues that can be segmented by:

  • Geolocation
  • Browser
  • Platform
  • Device
  • Time of Day

…and many other attributes. You can even compare traffic levels to performance issues to determine if you need extra capacity.

  TCP Port

The TCP Port monitor checks if a server is accepting TCP connection requests on a specific I.P. address port. No commands are sent, and the connection is immediately closed. This is used as a way to determine if services are accessible.

  Ping

The ping monitor simply tests if an I.P. address or host is responding to pings. This can be any device, as long as it supports the ICMP protocal and is not blocked by a firewall.