In After Effects you can simply do it using the system object, as Dirk mentioned. However you need several things for that:
checking that the script can access the network:
if (app.preferences.getPrefAsLong("Main Pref Section", "Pref_SCRIPTING_FILE_NETWORK_SECURITY") != 1) { alert("Please tick the \"Allow Scripts to Write Files and Access Network\" checkbox if Preferences > General"); // Then open Preferences > General to let people tick the checkbox app.executeCommand(2359); // Here you should check again if they ticked it, and choose to continue or stop ... }
checking of the OS:
var os = system.osName; if (!os.length) { // I never remember which one is available, but I think $.os always is, you'll have to check os = $.os; } app_os = ( os.indexOf("Win") != -1 ) ? "Win" : "Mac"
os-dependent system calls:
var url = "http://aescripts.com"; if ( app_os == "Win" ) { system.callSystem("explorer " + url); } else { system.callSystem("open " + url); }