How do I make the completion popup menu semi-transparent in Neovim?

Explanation

Neovim supports pseudo-transparency for the completion popup menu via pumblend and for floating windows via winblend. Setting these to a non-zero value lets you see the underlying text through popups, which can make the editing context easier to read.

How it works

pumblend is a global option (0–100) controlling the transparency of the completion popup menu:

set pumblend=10

Or in Lua:

vim.opt.pumblend = 10

winblend is a window-local option for floating windows. To apply it as a default to all new floating windows, use an autocommand:

autocmd FileType * lua vim.api.nvim_win_call(0, function()
  if vim.api.nvim_win_get_config(0).relative ~= '' then
    vim.wo.winblend = 10
  end
end)

Or set it directly when you open a floating window via the API:

vim.api.nvim_open_win(bufnr, false, { relative='cursor', winblend=15, ... })

• 0 = fully opaque (default)
• 100 = fully transparent
• 10–20 = a subtle, readable effect

Example

With set pumblend=15 active, pressing <C-n> opens the completion menu with a slight transparency, making the surrounding code visible behind it.

Tips

• Values above 30 tend to make the popup hard to read; 10–20 is the sweet spot
• This is a terminal feature — it requires true-color support (set termguicolors)
• Plugin floating windows (telescope, LSP hover) also accept winblend when configured in their setup options
• Pair with a theme that has a translucent popup background color for best results