A Go SSA callgraph builder and visualizer, by @protolambda.


  • output to generic Cytoscape JSON format. (list of nodes, list of edges)
  • output to a single html file, with js dependencies in unpkg, and graph data embedded.
  • outputs can be written to program output, or to a file.
  • use different SSA analysis types
  • support for Go-modules (powered by golang.org/x/tools/go/packages)
  • graph data is nested: packages > types / globals > attached functions
  • nodes are colored based on signature (50% parameters blend, 50% results blend)
  • all edges/nodes enhanced with classes to style/filter the graph with
go get github.com/protolambda/gocyto

Example output

This is the web output of the callgraph of Gocyto, including unexported functions:


Provide a Go package pattern to load the packages, and produce the call-graph.

gocyto github.com/user/project/some/package/...


gocyto [options...] <package path(s)>


  -build string
    	Build flags to pass to Go build tool. Separated with spaces
    	Include packages part of the Go root
  -mode string
    	Type of analysis to run. One of: pointer, cha, rta, static (default "pointer")
  -out string
    	Output file, if none is specified, output to std out
    	Consider tests files as entry points for call-graph
    	Include unexported function calls
    	Output an index.html with graph data embedded instead of raw JSON


To easily load packages into a SSA program, and construct callgraphs.

Loading packages:

program, err := analysis.RunAnalysis(withTests, buildFlags, packagePatterns)

Constructing a callgraph:


Supported callgraph analysis types:


Loads call-graph into a Cyto-graph object. After loading your graph (or multiple),
the data can be output to JSON to load with cytoscape.

Constructing a cyto graph:

// Base object, manages nodes, edges and keeps track of a [full-name -> ID] map for shorter IDs
cytoGraph := render.NewCytoGraph()

// more options to be decided on later, PRs welcome
opts := &render.RenderOptions{
    IncludeGoRoot: false,
    IncludeUnexported: false,

// add call graph from SSA analysis to cyto graph
err := cytoGraph.LoadCallGraph(callGraph, opts)

// add more call graphs if you like



  • Similar purpose
  • bloated/hacky code
  • uses deprecated SSA package loading
  • no re-usable library code
  • an ugly non-go Graphviz dependency
  • no Go module support.
  • limited styling
  • hacky build-tags support (overwriting the default Go build flags during runtime...)


  • minimal
  • outdated, 4 years old
  • limited callgraph information extracted
  • looks like the origin of godoc callgraph tool (???)


  • digraph and graphviz output support
  • doesn't add extra information (description/classes) to the calls
  • supports same set of analysis algorithms