Go panic stack trace analyzer

Paste a panic: output or goroutine dump — get the panic message, the crashing goroutine and all frames with file:line. Entirely in your browser.

How to read a Go stack trace

1. The panic: line is the what — e.g. index out of range, nil pointer dereference, or your own panic("…").
2. goroutine 1 [running] identifies the crashing goroutine. In dumps with many goroutines, find the one marked [running] near your panic.
3. Frame pairs — main.process(0x3) is the function, the indented line below (/app/main.go:12) is where in your code. The first pair after the goroutine header is the crash site.
4. +0x85 is the program counter offset — almost never what you need; the file:line above it is.

Common Go panics and their usual cause

• nil pointer dereference — a pointer/interface was nil; the first frame shows the line.
• index out of range — slice/array access past length; check the loop bound one frame up.
• concurrent map read and map write — shared map without a mutex; look for goroutines touching the same map.
• fatal error: all goroutines are asleep - deadlock! — channels that never receive; the dump shows who is waiting on what.

Is my trace uploaded anywhere?

No. This page is a single static HTML file — parsing runs entirely in your browser. Disconnect from the internet after it loads.

Need the full toolbox?

This page is one tool from LocalDevToolbox — trace analyzers for JavaScript/TypeScript, Python, Java, .NET and Rust, plus log doctor, context optimizer and more.