Chrome is currently at version 99 and Firefox at 98
In the past, some developers to get round buggy browsers wrote specific code that targeted specific versions.
The versions are identified by the User Agent string that the browsers send in the http headers
You can see what version you’re running in Chrome by entering in chrome://version/
At the time of writing, this is the latest version
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.51 Safari/537.36
What’s the issue with 3 digit User Agent Strings?
For most sites, nothing and they will continue to work fine.
The challenge is when developers wrote code that looked up the value of the user agent and deployed different code based on it’s value.
Typically they would have looked for a two digit value, and it’s unknown what will happen when it switches to 3 digits
For example, if you visit this page on the Manchester Evening news as Firefox 100, you’ll get a 403 error
There are 3 ways to test your site
Chrome UA Switcher Extension
This allows you to update the user agent string and emulate a browser.
It’s available from the Chrome Store
Once installed, select the Options menu
Then add the following into the boxes and press Add
New User-agent name:
New User-Agent String
Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/100.0.4844.51 Safari/537.36
You can now click on the icon in the toolbar
and select the Chrome and Chrome 100 option
The flag at the top will now tell you it’s changed
You can now visit your site and see if it’s working correctly
Screaming Frog Crawler
If you own this great SEO software program, there is already s blog post on Screaming Frog site that details how to change the user agent string
Set Chrome and Firefox flags
Both Chrome and Firefox allow you to change the setting to emulate this
Go to chrome://flags/#force-major-version-to-100
Set the dropdown to ‘Enabled’
Download and install Firefox Nightly
Open the settings and search for ‘Firefox 100’, and then enable ‘Firefox 100 User-Agent String’