heatseeker is described as 'General-purpose fuzzy selector focused on simplicity and performance'. There are eight alternatives to heatseeker for Mac, Linux, Windows, Vim and BSD. The best alternative is fzf, which is both free and Open Source. Other great apps like heatseeker are fzy (Free, Open Source), pick (fuzzy search) (Free, Open Source), icepick (Free, Open Source) and hf (Free, Open Source).
fzf is a general-purpose command-line fuzzy finder. * No dependencies * Blazingly fast * The most comprehensive feature set * Flexible layout using tmux panes * Batteries included * Vim/Neovim plugin, key bindings and fuzzy auto-completion