ack vs OpenGrok

ack has no write-up on Specifiction yet; its figures are above.

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.