This page has links to a number of resources that both DM’s and Players may find useful

Pathfinder / Starfinder

• Paizo – The publishers of the Pathfinder and Starfinder games
• d20pfsrd – an open source for the Pathfinder rules (except the proprietary content).
• starfindersrd – an open source for the Starfinder rules (except the proprietary content).

5th Edition D&D

• Wizards of the Coast – The Publishers of D&D. You can get the basic SRD (System Reference Document – the basic rules) from here free.
• DM’s Guild – A community driven publishing site where 3rd party content can be sourced.