OpenGrok vs Understand

OpenGrok is a Java source code search and cross-reference engine for searching and navigating source trees. It searches full text, definitions, symbols, paths and revision history, with subtree searches, wildcards and date-range filters. Its read-only web interface provides syntax-highlighted cross-references, file and directory history, and revision diffs. Supported revision control systems include Git, Mercurial, Subversion, CVS, Perforce, ClearCase, Bazaar, Monotone, Razor, RCS, SCCS, Teamware and AccuRev. Plugins can add support for programming languages or revision control systems. The web application provides a REST API under `/api/v1/` and a granular authorization framework; authentication is handled by the application server or a reverse proxy. Setup requires creating an index and deploying the web application. The guide lists Java 21 through 25, Universal Ctags and a servlet container such as Tomcat 10.x. OpenGrok is free and open source under the CDDL license, and is maintained by volunteers. Support and project requests go through discussions, mailing lists and GitHub Issues.

Understand is a static analysis and code-comprehension tool from SciTools. It builds a cross-referenced model of source code without executing it, then helps users explore relationships through its Information Browser, call trees, dependency analysis, and visual graphs, including butterfly and control-flow views. It also provides metrics, CodeCheck, version comparison, APIs, a command-line interface, and AI chat. Supported languages include C/C++, C#, Fortran, Java, Python, Rust, VHDL, Visual Basic, and web languages such as HTML, CSS, JavaScript, TypeScript, PHP, and XML. It runs on Windows 11, specified Linux distributions, and macOS Monterey or later; command-line automation, CI, and an official Docker image are also available. The VS Code extension is separately licensed. Local AI keeps code and prompts on the user's hardware, while cloud AI sends requests with code context to the selected provider. Offline use is supported with offline licensing. Pricing includes a free plan and paid subscriptions from $100/user/mo (annual).