You can install with Rust's cargo:

cargo install --git https://github.com/luizribeiro/clipsy

On your flake.nix, add clipsy as an input

{
  inputs.sops-nix.url = "github:luizribeiro/clipsy;

  outputs = { self, nixpkgs, clipsy }: {
    # change `yourhostname` to your actual hostname
    nixosConfigurations.yourhostname = nixpkgs.lib.nixosSystem {
      # customize to your system
      system = "x86_64-linux";
      modules = [
        ./configuration.nix
        clipsy.nixosModules.linux
      ];
    };
  };
}

With the module loaded, you can enable clipsy as a service:

{ ... }:

{
  services.clipsy.enable = true;
}

If you setup the overlay clipsy.overlays.default, you will be able to install clipsy to your PATH as well (which is necessary for the neovim and tmux integrations):

{ pkgs, clipsy, ... }:

{
  nixpkgs.overlays = [
    clipsy.overlays.default
  ];
  environment.systemPackages = with pkgs; [ clipsy ];
}

The instructions are the same as NixOS', with the difference that the module is clipsy.nixosModules.darwin instead of clipsy.nixosModules.linux.

With vim-plug, simply add to your config:

Plug 'luizribeiro/clipsy'

And anything copied through the registers + and * will be automatically synced to your clipsy server.

With tpm (Tmux Plugin Manager), simply add to your config:

set -g @plugin 'luizribeiro/clipsy'

And anything copied through tmux will be automatically synced to your clipsy server.