It’s possible that some parsing libraries may have hard-coded assumptions or bugs that don’t take into account three-digit major version numbers. Without a single specification to follow, different browsers have different formats for the User-Agent string, and site-specific User-Agent parsing.

When browsers first reached version 10 a little over 12 years ago, many issues were discovered with User-Agent parsing libraries as the major version number went from one digit to two. Why can a three-digit version number be problematic? Version 100 browsers will be first released in experimental versions (Chrome Canary, Firefox Nightly), then beta versions, and then finally on the stable channel.

The User-Agent and any other version reporting mechanisms will soon report a three-digit version number. Web developers use all kinds of techniques for parsing these strings, from custom code to using User-Agent parsing libraries, which can then be used to determine the corresponding processing logic. It also has the potential to cause breakage on websites as we move from a two-digit to a three-digit version number. Major version 100 is a big milestone for both Chrome and Firefox. Major version 100-three-digit version number It’s usually formatted as follows:įor example, the latest release versions of browsers at the time of publishing this post are: The string is also accessible through JavaScript with erAgent. User-Agent (UA) is a string that browsers send in HTTP headers, so servers can identify the browser. This post covers the timeline of events, the strategies that Chrome and Firefox are taking to mitigate the impact, and how you can help.

This has the potential to cause breakage on sites that rely on identifying the browser version to perform business logic. Chrome and Firefox will reach version 100 in a couple of months.

Firefox mobile user agent