A static analyzer analyzes reactive, critical, real-time programs written in the C programming language and looks for runtime errors. All possible errors are detected by the analyzer, with minimal "false alarms".

A small and smart programming tool that supports software engineering under C in the subjects modularity, overview and navigation (for Windows 9x/NT/2000). By Ezer Programmings.

Convert C preprocessed source to Java.

Allows C source files to be directly executed as scripts (using #!), speeding development and simplifying maintenance.

Acts as a caching pre-processor to C/C++ compilers, which often results in a 5 to 10 times speedup in common compilations. [Open Source, GPL]

Source-to-source translator for C, which analyzes the program to determine the smallest number of run-time checks that must be inserted in the program to prevent all memory safety violations.

An analysis and inspection tool that lets software developers and maintainers easily understand detailed dependence relations in source code.

Caches compiled object files to dramaticly speed up compiles. More convenient than make, and speeds up builds (like RPM builds) that make doesn't. Obsoleted by ccache.

A suite of C/C++ review, visualization and editing tools: Flowcharts, Tokens Panel, Comment Generator, and Auto-Formatting in real time, call/caller/file graphs.

Supports a wide range of software development activities, from easy editing to controlling source quality, from detailed reviewing to documenting. By RistanCASE.

Generates an index (or tag) file of C language objects found in C source and header files that allows these items to be quickly and easily located by a text editor or other utility. [Open Source, GPL]

A tool for formatting C code. [Open source, GPL]

An error detection tool for C/C++ that automatically finds hidden errors at the source code level.

Tool for statically checking C programs, GPL.

Source code analyzer, detects problems compilers cannot catch, by Cleanscape Software.

Colorizes identifiers and constants to show their marginal cost to the program's coupling and cohesion metrics. [GPL]

Check this site for a survey of source code comprehension tools (these show flow and/or relationships of function within the program in a graphical and/or text manner). Both free and commercial products are listed.

Vulnerability prevention tools for C language, embedded systems, and auto-generated code. Produces Sempre, a static analysis, code refactoring, and code comprehension system.