I made a package for taking actions when Authorize.net Webhooks hit your server (and soon to handle recurring subscriptions and protaing if you upgrade your plan before your next billing cycle).
https://github.com/joeelia/laravel-authorize-net-subscription-webhooks
I see a lot of questions about using SHA to verifiy the webhook paylod, this is already done in the package. Documentation is a bit scarce, but I will improve it as time goes on.
Enjoy.
