This is taking place amid massive and sometimes rather lengthy outages of the largest social networks and other online services that occurred earlier this month.
Thousands of users in the US reported that the American Express card system is not working, the Downdetector website's data shows.
According to the map of reported problems on the site, the highest number of complaints about the service are in the northeast of the country, in particular in New York, as well as in Los Angeles, California and Atlanta, Georgia.
Most of the Americans experiencing problems with American Express are claiming that they are unable to use their credit cards, which is about 76% of the total number of complaints.
The second most common problem is customer support, which does not work for about 18% of users.