cape.el - Let your completions fly!
Cape provides Completion At Point Extensions which can be used in combination with Corfu, Company or the default completion UI. The completion backends used by completion-at-point are so called completion-at-point-functions (Capfs).

You can register the cape-* functions in the completion-at-point-functions list. This makes the backends available for completion, which is usually invoked by pressing TAB or M-TAB. The functions can also be invoked interactively to trigger the respective completion at point. You can bind them directly to a key in your user configuration. Notable commands/Capfs are cape-line for completion of a line from the current buffer, cape-history for history completion in shell or Comint modes and cape-file for completion of file names. The commands cape-elisp-symbol and cape-elisp-block are useful for documentation of Elisp packages or configurations, since they complete Elisp anywhere.
Cape has the super power to transform Company backends into Capfs and merge multiple Capfs into a Super-Capf! These transformers allow you to still take advantage of Company backends even if you are not using Company as frontend.