Security is a diverse field of research and practice. Although there are tons of free and paid content on the Internet, it is often tricky to find good content that are suitable for people with various backgrounds such as developers, testers, researchers, enthusiasts. I'll be sharing links of good content here.
Bad Sector Labs Blog: Weekly news, techniques, tools, and technical articles
BleepingComputer and Hacker News: Daily security news and updates
Schneier on Security: Insightful news and articles from Bruce Schneier
APIsecurity.io: Periodic API security news and articles
Project Zero: Project Zero Team of Google sharing their latest findings with technical posts
Outflank Blog: Red teaming stories from the Outflank team
https://portswigger.net/research