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Github release Build status go-recipes Slack channel

go-callvis is a development tool to help visualize call graph of a Go program using interactive view.


The purpose of this tool is to provide developers with a visual overview of a Go program using data from call graph and its relations with packages and types. This is especially useful in larger projects where the complexity of the code much higher or when you are just simply trying to understand code of somebody else.


  • click on package to quickly switch the focus using interactive viewer
  • focus specific package in the program
  • group functions by package
  • group methods by their receiver type
  • filter packages to specific import path prefixes
  • ignore calls to/from standard library
  • omit various types of function calls

Output preview


Check out the source code for the above image.

How it works

It runs pointer analysis to construct the call graph of the program and uses the data to generate output in dot format, which can be rendered with Graphviz tools.

Quick start



  • Go 1.19+
  • Graphviz (optional, required only with -graphviz flag)

To install go-callvis, run:

# Latest release
go install

# Development version
go install

Alternatively, clone the repository and compile the source code:

# Clone repository
git clone
cd go-callvis

# Compile and install
make install


Interactive viewer

To use the interactive view provided by a web server that serves SVG images of focused packages, you can simply run:

go-callvis <target package>

HTTP server is listening on http://localhost:7878/ by default, use option -http="ADDR:PORT" to change HTTP server address.

Render static output

To generate a single output file use option -file=<file path> to choose output file destination.

The output format defaults to svg, use option -format=<svg|png|jpg|...> to pick a different output format.


Usage of go-callvis:
    	Enable verbose log.
  -file string
    	output filename - omit to use server mode
  -cacheDir string
    	Enable caching to avoid unnecessary re-rendering.
  -focus string
    	Focus specific package using name or import path. (default "main")
  -format string
    	output file format [svg | png | jpg | ...] (default "svg")
    	Use Graphviz's dot program to render images.
  -group string
    	Grouping functions by packages and/or types [pkg, type] (separated by comma) (default "pkg")
  -http string
    	HTTP service address. (default ":7878")
  -ignore string
    	Ignore package paths containing given prefixes (separated by comma)
  -include string
    	Include package paths with given prefixes (separated by comma)
  -limit string
    	Limit package paths to given prefixes (separated by comma)
  -minlen uint
    	Minimum edge length (for wider output). (default 2)
  -nodesep float
    	Minimum space between two adjacent nodes in the same rank (for taller output). (default 0.35)
    	Omit calls to unexported functions.
    	Omit calls to/from packages in standard library.
        Direction of graph layout [LR | RL | TB | BT] (default "LR")
    	Skip opening browser.
  -tags build tags
    	a list of build tags to consider satisfied during the build. For more information about build tags, see the description of build constraints in the documentation for the go/build package
    	Include test code.
    	Show version and exit.

Run go-callvis -h to list all supported options.

Reference guide

Here you can find descriptions for various types of output.

Packages / Types

Represents Style
focused blue color
stdlib green color
other yellow color

Functions / Methods

Represents Style
exported bold border
unexported normal border
anonymous dotted border


Represents Style
internal black color
external brown color
static solid line
dynamic dashed line
regular simple arrow
concurrent arrow with circle
deferred arrow with diamond


Here is an example for the project syncthing.

syncthing example

Check out more examples and used command options.


Join #go-callvis channel at (not a member yet? get invitation)

How to help

Did you find any bugs or have some suggestions?

  • Feel free to open new issue or start discussion in the slack channel.

Do you want to contribute to the project?

  • Fork the repository and open a pull request. Here you can find TODO features.


The interactive tool described below has been published as a separate project called goexplorer!

Ideal goal of this project is to make web app that would locally store the call graph data and then provide quick access of the call graphs for any package of your dependency tree. At first it would show an interactive map of overall dependencies between packages and then by selecting particular package it would show the call graph and provide various options to alter the output dynamically.