This might be news for some, but Firefox does not have all the features available for all the geographical locations. The reason for this is nothing malicious I would say, it's simply because i18n is hard.

So I was quite surprised to learn that there is no address autofill available in my Firefox installation. Something so convenient I can't imagine using web browser without it.

After a little bit of research I found a lot of outcries [1,2,3] on the Mozilla support forum, some generic help pages that briefly mentioned that this feature is US only [4] and finally a little bit more useful wiki with proper breakdown of the feature availibility [5].

So the way to enable form/address autofill for non-US country is:

1. Put into address bar about:config and click Accept the risk and continue
2. Search for following and set:
   • extensions.formautofill.available: on
   • extensions.formautofill.creditCards.available: true
   • extensions.formautofill.supportedCountries: GB (this settings depends on where you live - check ISO 3166)
3. Restart firefox
4. Check on the somewhat official Firefox address autofill demo that the feature works for you