Callgraph.io – Visualize the code flow of complex databases and system softwares

Hi HN,

I built Callgraph.io, a web app designed to visualize the code flow of complex databases and system softwares to help developers understand the source code.

The problem: I spend a lot of time diving into massive, complex codebases—particularly database like Valkey, PostgreSQL, RocksDB. Trying to trace execution paths for things like query parsing or B+ tree implementations across thousands of lines of C, C++, or Go can get overwhelming quickly. I constantly found myself lost in a maze of tabs and IDE windows just trying to hold the execution context in my head.

The Solution: I wanted a bird's-eye view. With, Callgraph.io I mapped the codebase of several databases and system softwares to create interactive visualizations of the execution flow. It makes it significantly easier to understand the relationship between different source files and functions. I also added a "one-click AI insight" feature to get a quick summary of what a function does, among other tools.

This is primarily aimed at engineers who are at the beginning of their journey into database internals, rather than seasoned experts.

I'd really appreciate your feedback!