Standard Action is described as 'tabletop gaming application designed to be simple, but flexible. In game, Standard Action features an interactive game board, live chat, dice rolls, a turn tracker, customizable token stat bars, and much more' and is a Virtual Tabletop in the category. There are more than 25 alternatives to Standard Action, not only websites but also apps for a variety of platforms, including Windows, Mac, Android and Linux. The best alternative is Roll20, which is free. Other great sites and apps similar to Standard Action are D&D Beyond (Freemium), MapTool (Free, Open Source), Owlbear Rodeo (Free) and Fantasy Grounds (Paid).
Roll20 is the free, easy way to play tabletop games (such as pen and paper RPGs) online with others. It's completely web-based, so it runs right in your browser. It supports video and voice chat, background music, character sheets, a massive art library, and more!
MapTool is an online, multiuser, networked, graphical, interactive, programmable virtual tabletop. Requires Java 6+. It can be used for face-to-face play, or Internet role-playing in real time even if your players are on the other side of the world.
Owlbear Rodeo is a simple VTT that requires no registration and offers map sharing and drawing, dice rolling, voice chat, and other features that allow for a simple-to-use tabletop encounter experience.
Beyond Tabletop is a set of tools for RPG players with easy-to-use online character sheets and maps. Subscription-free and designed to be used on all devices online. Currently offering a battle map and character sheets for Pathfinder and D&D 5e.