Simbrief was aquired by Navigraph in April 2021 where Derek the developer still plays a pivotal role. Simbrief remains free to use with a fixed AIRAC that is periodically updated, a Navigraph subscription is required should you require active AIRAC.
Without doubt it is an excellent product especially for retrieving routes whether those published by users or now the enhanced realworld coverage. If however you are looking to plan your own routes then PFPX is still far easier to use whereby you can create your own direct links for automatic routing, create and avoid restricted areas and automatically use your defined sub-routes.
Whilst me may have lost the online data hopefully the activation server remains active (or an alternative means made available), which was the case when I tested following flightsimsoft.com going offline.