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alt is a command line utility that attempts to find the "alternate path" for the provided path.

The "alternate path" could be the test file associated to the implementation file you gave it the path for. Or, it could be a lock file for a dependency specification file. Or, it could be an implementation file associated with an interface file. alt works by analyzing the similarity between file names and paths to identify the "alternate path" such that it can be used across many different use cases.

This is primarily intended for developers. It is written in Rust. Hence, it is compiled and distributed as a binary.

It was originally written to alternate files in vim, but has no dependency on vim at all and can be used in many other scenarios as it is just a command line utility.

Its interface is as simple as they come.

  • Pass it a path as the first argument
  • It will print the alternate path to standard out

For example:

$ alt spec/app/queues/fee/user_fee_submission_spec.rb


For advanced usage, full reference of the command line interface, and frequently asked questions please refer to the Wiki.


If you are on a platform other than macOS or Arch Linux you will have to build your own version from source.


To install on macOS we provide a Homebrew tap which provides the alt formula. You can use it by doing the following:

Add the Tap

brew tap "uptech/homebrew-oss"

brew install

brew install uptech/oss/alt

Arch Linux

Install from the AUR:

git clone
cd alt
makepkg -si

Build from Source

If you are on another platform you will have to build from source. Given that alt is managed via Rust's Cargo. It can build as follows:

$ cargo build --release

Once you have built it successfully you should relocate the target/release/alt binary to a location that exists in your PATH so that you can easily use it. You should also relocate the doc/alt.1 man page to the appropriate location.

Note: The above requires of course that you have rust and Cargo.

Use with Vim

There's no vim plugin. It may not end up needing one; we'll see. For now, you can just stick the code below in your .vimrc to invoke alt with <leader>.. Note that alt and the Vim Script example below work in both the terminal based Vim and GUI based Vim like MacVim.

" Run a given vim command on the results of alt from a given path.
" See usage below.
function! AltCommand(path, vim_command)
  let l:alternate = system("alt " . a:path)
  if empty(l:alternate)
    echo "No alternate file for " . a:path . " exists!"
    exec a:vim_command . " " . l:alternate

" Find the alternate file for the current path and open it
nnoremap <leader>. :w<cr>:call AltCommand(expand('%'), ':e')<cr>

Ignoring Things

alt by default ignores hidden directory entries, globs defined in a .ignore file and globs defined in your project's .gitignore and your global .gitignore. It does this because in our experience that is generally the behavior you want. If however you want for example to be able to alternate between hidden files for some reason, you can always use the -a option. If you want to have alt ignore some specific paths/files that you don't want Git to ignore. You can simply define them in the .ignore file at the root of your project.


If you interested at all in contributing. Please do. We are welcoming group and are willing to provide guidance whenever possible.

Please see for more details on contributing.


alt is Copyright © 2016 - 2021 UpTech Works, LLC. It is free software, and may be redistributed under the terms specified in the LICENSE file.

About uptech

alt is maintained and funded by UpTech Works, LLC, a software design & development agency & consultancy.

We love open source software. See our other projects or hire us to design, develop, and grow your product.