Be aware that this page describes NameTag 1. You might be also interested in visiting NameTag 3.
NameTag Online
NameTag Web Application is available at http://lindat.mff.cuni.cz/services/nametag/ using LINDAT/CLARIN infrastructure.
NameTag REST Web Service is also available, with the API documentation available at http://lindat.mff.cuni.cz/services/udpipe/api-reference.php.