Choosing Neovim’s Built-in LSP vs External Plugins

Problem and takeaway

You need language support in Neovim without spending time configuring a full plugin stack. The useful takeaway: Neovim ≥ 0.5 with Lua includes a built-in LSP client that starts quickly and works out-of-the-box for basic diagnostics, completion, and goto-definition. If you need rich fuzzy completion, snippets, or advanced code actions, an external plugin such as nvim-lspconfig plus nvim-cmp gives you that UI at the cost of extra bundle size and a Node.js dependency.

Decision and constraints

Before adding any code, check two constraints:

• Neovim version: run nvim --version and confirm +lua and +client-server features are listed. Older releases (< 0.5) lack the built-in client.
• Lua availability: the built-in client is driven from Lua; if your Neovim was compiled without +lua you must rebuild or use Vimscript fallbacks.

If both are present you can enable the built-in client immediately; otherwise you will need the external stack.

Comparison table

Feature	Built-in LSP client	External plugins (nvim-lspconfig + nvim-cmp)
Startup latency	Low – client starts with Neovim, no extra process launch	Higher – each language server starts on demand; plugin loading adds a few milliseconds
Completion UI	Minimal – default completion list, no fuzzy matching	Rich – fuzzy matching, icon picker, snippet insertion via nvim-cmp
Snippet support	None built-in	Yes – via nvim-cmp source snippets
Lifecycle management	Neovim starts/stops the language server automatically	Plugins manage startup, shutdown, and per-language configuration
Configuration effort	Lua API calls or :LspStart command	Typical lspconfig setup tables plus cmp mapping
Bundle size	Core Neovim only	Adds lspconfig, cmp, and often Node.js runtime

Trade-offs

Choose the built-in client when you want quick setup, low resource usage, and you are comfortable with basic completion lists. It stays in sync with core releases, so you rarely need to update a plugin. Pick the external stack when your workflow depends on fuzzy completion, snippet expansion, or you want fine-grained control over server arguments and auto-installation. Note that running two LSP clients simultaneously can cause conflicts; keep only one active per buffer.

Concrete implementation

Below is a minimal Lua snippet that activates the built-in LSP for Python files. Place it in ~/.config/nvim/init.lua:

-- Enable the built-in LSP client for Python
vim.api.nvim_create_autocmd('FileType', {
  pattern = 'python',
  callback = function()
    -- Start the language server if it isn't already running
    if not vim.lsp.get_active_clients({ bufnr = 0 })[1] then
      vim.cmd('LspStart python')
    end
  end,
})

After saving the config, open a Python file and run :LspStart python (or let the autocmd do it). Diagnostics appear in the Messages area, and you can navigate errors with ]e and [e. To verify the client is active, run :LspInfo; the output lists the attached language server and its capabilities.

Verification steps

1. Run nvim --version and confirm +lua and +client-server appear.
2. Open a Python file.
3. Execute :LspStart python.
4. Check that diagnostics are shown with :messages or the sign column.
5. Run :LspInfo to see the server name and supported features.

If you are using an external plugin stack, install nvim-lspconfig and nvim-cmp via your package manager, then consult their respective READMEs for server-specific setup. Compare completion latency and UI richness subjectively.

Limitations

The built-in client does not expose every language-server feature. Code actions, advanced type-hierarchy traversal, and some diagnostic codes may be missing or limited. Additionally, the client's completion source is not fuzzy-matched; you will not get the 'fuzzy-find-as-you-type' experience without nvim-cmp. Finally, if you have multiple language servers attached to the same buffer, Neovim may prompt you to choose one; keep your configuration focused on a single language per file type to avoid ambiguity.

Wrap-up

For most day-to-day editing, the built-in LSP client provides enough functionality to replace a full plugin stack while keeping Neovim lean. When you need richer completion, snippets, or programmatic control over server lifecycle, add nvim-lspconfig and nvim-cmp deliberately. The Lua snippet above gets you started with the built-in client in under a minute.