This is a curated list that I’ll add to periodically. If you know of anything that could go well here, not just compilers lints, formatters, IDEs for C, please let me know via the contact form.

• A source code formatter for C, C++ and other programming languages.
• Algorithms website. Over 150 C implementations each with a video and source code. Plus other programming language algorithms.
• Cheerp is an enterprise-grade C/C++ compiler for the Web that can compile C/C++ into WebAssembly and JavaScript and is open source, with dual licence (GPLv2 & commercial).
• Clang is a C family (C, C++, Objective C/C++, OpenCL, CUDA, and RenderScript) compiler for the LLVM project. Both a GCC-compatible compiler driver (clang) and an MSVC-compatible compiler driver (clang-cl.exe) are provided.
• Devart Code Compare is a very handy way to compare two files. It integrates with Visual Studio but not Visual Studio Code. There’s a free version or a paid version.
• Pelles C is a complete development kit for Desktop Windows. It includes an optimizing C compiler, a macro assembler, a linker, a resource compiler, a message compiler, a code signing utility, a make utility and an install builder. Also check out their source code page.
• Portability and the C language. An eBook on WIkibooks about porting C programs and possible problems.
• Project based tutorials in C. On databases, networking, programming languages and operating systems plus even a bit on Blockchain.
• Simple HTTP server serving static web-pages in C.
• Visual Studio Code – a totally free cross-platform IDE for most languages with extensions from Microsoft. Probably the best IDE on Linux (IMHO!)

Recommended Visual Studio Code Extensions

• Diff & Merge. Still at alpha but provides file diff and merge capabilities.