WebsitebeginnerFree
Fangraphs
Unknown
Advanced stats and player analysis
More resources on Baseball
WebsiteFree
Baseball-Reference
Comprehensive player and team stats
WebsiteFree
Driveline Baseball
Science-based training resources
WebsiteFree
Baseball Savant
Statcast data visualizations
VideoFree
Eric Cressey Baseball Mobility
Highly upvoted shoulder prep routine
VideoFree
OnBaseU Hitting Drills
Practitioner-favorite free drills playlist
VideoFree
Tread Athletics - Swing Training
Top recommended swing mechanics series from r/Homeplate