Real Golf Scorecard is a free web site, with an associated mobile app, that lets you enter your scores directly into a full 18-hole online golf scorecard, instead of entering your scores one hole at a time.
USGA Handicap calculations are included.
It works in all modern mobile web browsers.
The first step is to take a minute to create a free user account, starting from the "Register" button in the menu.
The second step is to create a Course for your Round, starting from the "Courses" button in the menu.
The third step is to add a few Players for your Round, starting from the "Players" button in the menu.
The final step is to setup your Round and open your Scorecard, starting from the "Rounds" button in the menu.