Show HN: A open-source, local trace viewer for Claude Code and Codex sessions (opens in new tab)

I built this because I had a hard time investigating why certain Claude Code subagent/skills were performing poorly. Regular old, boring software has had profilers and debuggers for decades. When a request is slow or a function blows up memory, you have tools that tell you exactly where.

In the new world order of agentic development, poor performance is usually due to context bloat - either too many unnecessary tokens or missing relevant ones. I wrote this to help answer questions like:

- Which tool calls ballooned the context window, and on which turn? - What context was the subagent/skill passed when it was spawned? - What steps were repeated every session that could be lifted into a skill/documentation or cached lookup?

Agent Profiler is the tool for just that. It requires zero setup (just node), is fully local, open-source and can support any agent harness with a local transcript format.