LXR Cross Referencer, usually known as LXR, is a general-purpose source code indexer and cross-referencer for code comprehension that provides web-based browsing of source code, with links to the definition and usage of any identifier. History LXR was born from a need for a tool to keep a synthetic eye on the Linux kernel during its development (whence its original name: LXR stood for "Linux Cross-Referencer"). Such a tool is all the more necessary as documentation is scarce and contributor number is high. Two Norwegian students, Arne Georg Gleditsch and Per Kristian Gjermshus, curious about Linux architecture, began writing a small program displaying its files through a web-browser and showing variables usages after a click on the name. Aware of general interest, they posted it rapidly on SourceForge (as early as 1994?). Time passing, fans joined the development team to give code more maturity; however their number never exceeded ten. With these characteristics, LXR is a typical SourceForge-hosted project but exhibits an exceptional life duration among small projects. One of the initial creators explored new technologies giving the LXRng spin-off. This experimental development does not contain all features present in the traditional version and departs notably from LXR founding principles. Though no communication was really ever done around the tool, LXR made its way through some paper columns, e.g. Linux Journal. However, when collecting references to LXR on the Internet, there is ambiguity between the tool itself and instances of LXR displaying indexed source code (since many sites use "LXR" in its original sense of "Linux Cross-Referencer"). After adopting LXR to index the source code for the Mozilla Application Suite, Mozilla forked LXR to into MXR (the Mozilla Cross Reference). MXR was forked in order to meet the needs of Mozilla development, namely code navigation of a mixed C++ and JavaScript codebase. After years of MXR use, Mozilla began work on a new tool with a focus on better static analysis and a dynamic Ajax UI. The result is DXR (the Dehydra Cross Reference). After DXR reached maturity, the MXR instance at mxr.mozilla.org was decommissioned. Technology LXR is minimalist and adheres to the least-effort principle. The deliberate bias towards minimalism avoids using too many different technologies. Thus, it limits the dependencies and the software can be supported by many configurations without special adaptation. The design choices include interpreted languages (such as Java or JavaScript) barring or strict HTML 4.01 conformance.