gofindimpl

Hunt down Go interface implementations like a bloodhound with trust issues.

You point gofindimpl at an interface in a Go file and a directory to search. It parses the packages under that directory, keeps the structs that have a method for each method name in the interface, and prints them as a JSON array on stdout. No grep, no guessing, no 3am existential crisis.

gofindimpl \
  -interface ./internal/app/server.go:Server \
  -dir ./internal/pkg/

[
  {
    "package": "impl",
    "struct": "WebServer",
    "packagePath": "github.com/yourproject/internal/pkg/impl"
  }
]

Install

go install github.com/psyb0t/gofindimpl@latest

Or run it without installing anything:

go run github.com/psyb0t/gofindimpl@latest \
  -interface ./path/to/file.go:InterfaceName \
  -dir ./search/directory

Or clone and build it like it’s 2005:

git clone https://github.com/psyb0t/gofindimpl.git
cd gofindimpl
go build -o gofindimpl

The module declares go 1.26 in its go.mod, so you need Go 1.26 or newer to build it. Run it from the root of the module you are searching, the directory that holds its go.mod.

Where to go next

You want to	Read
See every flag, the interface spec format and the JSON output	Command line
Know exactly what counts as an implementation, and what gets missed	How it works
Decode an error message	Troubleshooting
Build, lint and test gofindimpl itself	Development

The source is on GitHub.