How to use a derivation in a flake?

Hi all

Been experimenting with NixOS and it’s been great so far.

I did come across an application that I need to install but it is not in nixpkgs and I’m wondering how to install this. It’s an application which I can find the executable binary on the product website. I searched the internet and there is some suggestion to create a derivation which I did. But I don’t know how to load this in my flake. I couldn’t find any example of how to do this.

{ lib, stdenv, fetchurl, ...}:

stdenv.mkDerivation rec {
    name = "stereo_tool_gui_jack_64";
    version = "10.30";
    src = fetchurl {
        curlOpts = [ "-L" ];
        url = "";
        sha = "b32d69b3892732548a55aa5241327afbc43bc7bd3f0a94548fb524596524ada2";

    installPhase = ''
        mkdir -p $out/bin
        mkdir -p $out/share/applications
        cp $src $out/bin

I saved this file in my flake project. But how do I call this?

This should do it

stereo_tool_gui_jack_64 = pkgs.callPackage ./path/to/file.nix { };

Maybe this project might help you: GitHub - drupol/my-own-nixpkgs: Scaffold