- cppreference.com first on the list, a fantastic resource and bang up-to-date; this is my first point of reference as it often saves time compared to looking in a book
- C++ Annotations is a continuously improving text book (tracking developments in the C++ language and Standard Library) available in both HTML and PDF (10.1MB) format with a lot of useful content
- C++ “Super” FAQ for Frequently Asked Questions arranged in a semi-tutorial style; partially updated for modern C++ and still a works-in-progress
- CppCoreGuidelines a large HTML document aimed at intermediate and above programmers concerning modern best practices, worth a look
- Fluent C++ my favorite C++ blog with two posts per week on average, and a focus on using the Standard Library
- C++ Weekly several years in the making with many interesting insights into modern features of C++ in bite-sized video format
- Compiler Explorer is great for comparing different compilers and versions, sharing code and even running test programs quickly
And if you’re ever looking for something completely different (while still programming) try this link.