Understand - Combines a powerful Code Editor together with an impressive array of static analysis tools that will change the way you work with code.
OpenGrok - OpenGrok is a fast and usable source code search and cross reference engine.
Sourcetrail - Sourcetrail is a cross-platform source explorer for C/C++ and Java.
Sourcegraph - Sourcegraph is a free, self-hosted code search and intelligence server that helps developers find, review, understand, and debug code. Use it with any Git code host for teams from 1 to 10,000+.
Source Insight - Source Insight is a programming editor & code browser with built-in live analysis for C/C++, C#, Java, and more; helping you understand large projects.
DXR - Powerful code search for large codebases.