Drivethru RPG

Nowadays, most RPGs have PDFs available for purchase here — D&D 5e being the notable exception.

D&D Beyond

See the section on D&D Beyond.

Online SRDs

Some games have great online SRDs. Here are some examples:

• D&D 5e
• Pathfinder 1e
• Pathfinder 2e
• FATE
• 13th Age
• Dungeon World
• Blades in the Dark
• Open Legend RPG
• Mutants & Masterminds
• Basic Fantasy RPG
• Degenesis