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Preview of CheckMyHTTPS

CheckMyHTTPS by CheckMyHTTPS Team

CheckMyHTTPS ensures that your secured WEB connections ('HTTPS' protocol) are not intercepted (neither decrypted, nor listened, nor modified).

4.4 (10 reviews)4.4 (10 reviews)
193 Users193 Users
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Extension Metadata

Screenshots
Here is the meaning of check logosHere is what happens when you decide to check your HTTPS connectionHere are the options available
About this extension
When browsing on secured sites ("https://..." websites), you can check the security status by clicking on the extension icon (check).
  • The icon is green : your connection is not compromised;
  • The icon is red : your connection is considered very risky (hijacked, modified, listened);
  • The icon is gray : the verification is impossible (check server is unreachable, network error);
  • The icon is black : the verification is in progress.

Technical details :
Normally, before encrypting an HTTPS connection, a secure website must prove its identity to your browser by sending it its security certificate. This certificate can be considered as an identity card issued by higher authorities (Certificate Authorities). There are several techniques of usurpation based on false certificates (false identity cards) or homographers (false names) to make you believe that a "pirate" site is the legitimate site you think you are visiting. These techniques allow pirate sites to retrieve your private information.
CheckMyHTTPS allows you to detect this type of practice, which can be implemented on open networks (WiFi in hotels, conference centers, stations, etc.) or even within your company via its firewall (SSL inspection). To detect this, the extension compares the certificate of the visited site that is received by your browser with the same certificate retrieved by an external "verification server" located on the Internet. If the certificates differ, the identity of the server can be considered as usurped (red icon).

Respect for privacy?
The CheckMyHTTPS extension requires only two parameters : The name of the visited website and the certificate received from it;
The external verification server only receives the name of the visited website. If you want, you can make this verification server yourself.

All explanations are detailed on the https://checkmyhttps.net project website.
Rated 4.4 by 10 reviewers
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Permissions and dataLearn more

Required permissions:

  • Display notifications to you
  • Access browser tabs

Optional permissions:

  • Access your data for all web sites

Data collection:

  • The developer says this extension doesn't require data collection.
More information
Add-on Links
  • Homepage
  • Support site
  • Support Email
Version
5.7.2
Size
58.35 kB
Last updated
2 days ago (14 Sep 2025)
Related Categories
  • Privacy & Security
Licence
GNU General Public Licence v3.0 only
Privacy Policy
Read the privacy policy for this add-on
Version History
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Release notes for 5.7.2
  • Visual improvement of Options page
  • Handle the case of checking addons.vaultpit.io's certificate which is not possible due to a safety feature where Firefox prevents its extensions from manipulating the extension store website
  • By default, the extension icon is icon.png, not unknown.png anymore.
  • Improved error handling messages
  • Reorganized and improved localization messages
  • Removed severalCertificates 'SC' case handling. It is now considered invalid.
  • Checking an IDN (Internationalized Domain Name) website is now considered valid (as long as both certificate fingerprints are equal).
  • Made the IDN warning notification clickable to redirect the user to wikipedia's IDN homograph attack page
  • Removed Warning status as severalCertificates and IDN cases are no longer considered warning
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