More user friendly than Runsweet in my opinion.
Excarbs provides some useful resources and guidance for dealing with exercise as a T1, however, treat the calculator with a pinch of salt and make sure you work out for yourself whether the guidance it provides will work for you through testing around the exercise you undertake.
Editorial Team Note
Please note that the comments on the ExCarbs website seem to be almost entirely unmoderated. The review of this resource explicitly excludes any websites mentioned in the user-generated comments.