Free, Linux-Native, Multi-Window Code Reader With LSP-Powered Click-Through Call Graphs (Source Insight UX Without the License)

dev tool weekend hack •• multiple requests

Multiple HN devs in the December 2025 'developer tool you wish existed in 2026' thread asked for a Source-Insight-style code reader: open a function in window A, click any callee, the new window pops with proper highlighting, struct definitions stick to the bottom, all panels stay open at once. Source Insight is paid Windows-only. Crabviz is LSP-aware but VS Code-only and just renders graphs. Sourcetrail is unmaintained. Source-Navigator NG is dated. Nothing combines persistent multi-pane navigation + LSP language-agnosticism + Linux-native + free.

builder note

Tauri or GTK4 + tree-sitter for incremental highlighting + any LSP backend the user already has installed. Don't re-implement parsers... lean on the LSPs already on the dev's machine. Ship it as a single binary that opens to a shortcut launcher of recent functions, not yet another sidebar plugin.

landscape (5 existing solutions)

The space is littered with half-tools: each gets one axis right (LSP, multi-language, Linux, free, multi-pane, interactive) but never all of them at once. The exact UX a kernel-source reader wants — a tiling-window 'browser for code' — doesn't exist on Linux as a free LSP-driven app.

Crabviz VS Code-only, generates static call graphs, doesn't have the multi-pane stay-open exploration UX. Useful for one-off graph rendering, not for sitting in the codebase reading it.

Sourcetrail The closest spiritual successor, but the company shut down and the project is unmaintained. New language support requires forks. No active LSP wiring.

Source-Navigator NG Pre-LSP era. Custom parsers, limited language coverage, dated UI, sporadic maintenance.

Understand by SciTools Excellent UX but commercial, expensive seat license. Useless for hobbyist OS-source-reading like xv6 or Linux kernel.

Woboq Code Browser Web-only, static HTML, C/C++ focus. Designed for reading published source on a website, not interactive in-IDE exploration.

sources (3)

hn https://news.ycombinator.com/item?id=46345951 "VSCode Peek definition but with a different visual style... source insight but free and in Linux" 2026-02-09

hn https://news.ycombinator.com/item?id=46352468 "experimented with this... using the Language Server Protocol to make it somewhat universal" 2026-02-10

other https://alternativeto.net/software/source-insight/?platform=... "best Linux alternative is Understand. However, it's not free" 2026-04-10

code-readinglsplinuxdeveloper-toolsopen-source