After many years of not showing Southwest Airlines flights, Google Flight now shows these flights. There is no need to painfully search through the Southwest website—particularly if you are looking at multiple destinations at once.
You can also track prices using Google flights and rebook for free if a lower fare becomes available. This is very helpful to customers, and hopefully, free rebooking on Southwest will not disappear with this change.
It was never entirely clear why Southwest Airlines chose not to display fares on third-party websites. Popular theories range from the dynamic nature of Southwest routes to controlling inventory, which is certainly a welcome change.