shougo/deoplete.nvim

Deoplete is an auto-completion plugin for Neovim and Vim 8, the text editors commonly used by programmers who prefer working in a terminal. When you are writing code in one of those editors, deoplete watches what you type and shows a dropdown list of suggestions to complete the current word, function name, or variable, without you needing to pause and look them up. The completion happens in the background without freezing the editor, which is what the README means by asynchronous. The plugin does not provide completions on its own. Instead, it acts as a framework that other, more specific plugins can connect to. Those connector plugins, called completion sources, supply the actual suggestions for particular languages or tools. There are sources available for Python, JavaScript, TypeScript, Go, C++, Rust, Ruby, C#, F#, and others, as shown in the screenshots in the README. To use it, you need Neovim 0.3.0 or later (or Vim 8.2.1978 and above) with Python 3.6.1 or later installed, plus a Python package called pynvim. Installation is done through a Vim plugin manager like vim-plug or dein.vim, and the README includes the exact configuration lines to paste in. For regular Vim 8 users (not Neovim), two additional compatibility plugins are required. An important note at the top of the README: development on deoplete is finished. The author has moved on to a newer plugin called ddc.vim and recommends that new users start there instead. Deoplete still accepts small bug fixes but will not gain new features. Existing setups that rely on it will continue to work, but migration to the newer plugin is encouraged.