Merlin
Certificate expiration

Certificate expiration

Shows how many days the website certificate has left until is expires.

What is Certificate expiration?
Certificate expiration is a Firefox add-on that checks the number of days left until the certificate for the current page expires. It displays the day count on top of a padlock icon in the toolbar and turns red if there are less than 29 days left. It also shows an unlocked red padlock if the site connection is not encrypted.
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Merlin
Stats
By: Johan
Users: 153 ▲ 2
Rating: 4.50 (4)
Version: 3.0 (Last updated: 2023-07-21)
Creation date: 2020-03-01
Weekly download count: 5
Firefox on Android: No
Risk impact: High risk impact
Risk likelihood: Moderate risk likelihood
Manifest version: 2
Permissions:
  • webRequest
  • webRequestBlocking
  • <all_urls>
  • tabs
Size: 53.75K
URLs: Website
Stats date:

Chrome-Stats Rank

# 8021 ▲ 83
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Other platforms

Not available on Chrome
Not available on Edge
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Merlin
Summary
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This is a simple Firefox extension that checks the number of days left until the certificate for the current page expires and displays it to the user.

It then shows the day count on top of a padlock icon in the toolbar. If there are less than 29 days left of the certificate the icon turns red. If the site connection is not encrypted it shows an unlocked red padlock instead.

User reviews
Great for being alert to SSL certificates that are about to expire. Note that the colour-changing padlock is a new button (it doesn't change the browser's existing padlock), and that in 2023-era Firefox you have to add this yourself. Firefox doesn't show it among the ‘Customise Toolbar’ buttons; instead, you now need to go to the ‘jigsaw’ button which lists extensions, then click on the gear for ‘Certificate expiration’ and choose ‘Pin to Toolbar’. You can then use ‘Customise Toolbar’ to drag it to where you want it. And also note that Mozilla blocks extensions on this Add-Ons site, so this isn't a good page for trying it out and seeing how it works!
by Smylers, 2023-02-06
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Safety
Risk impact

Certificate expiration is risky to use as it requires a number of sensitive permissions that can potentially harm your browser and steal your data. Exercise caution when installing this add-on. Review carefully before installing. We recommend that you only install Certificate expiration if you trust the publisher.

Risk likelihood

Certificate expiration is probably trust-worthy. Prefer other publishers if available. Exercise caution when installing this add-on.

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