Both extensions stop you from opening distracting websites, but they take different approaches. BlockSite leans toward scheduled blocking with an optional account and mobile app, while StayFocusd is a lighter, local tool built around a daily time budget for specific sites.
Scheduling focus time vs a daily time limit
BlockSite lets you set blocking schedules, such as blocking social media during work hours, and its paid tier adds more scheduling flexibility. StayFocusd instead gives each blocked site a shared daily time allowance; once you use it up, the sites are blocked until the next day, which suits a simpler all-or-nothing approach.
Account requirements and cross-device sync
BlockSite can sync your blocklists and schedules across devices when you create an account, including a mobile app. StayFocusd works locally in the browser without an account, so your settings stay on that one browser and don't carry over to your phone or another computer.
Blocking strictness and getting around it
Both let you block specific sites, but StayFocusd's nuclear option locks you out of chosen sites for a set period with no easy way to undo it early. BlockSite's paid plan includes a password-protected mode to stop you from disabling the blocker mid-session, which is closer to the same idea.