return {
    'nvimtools/none-ls.nvim', -- configure formatters & linters
    event = { 'BufRead', 'FileType' },
    dependencies = {
        'jay-babu/mason-null-ls.nvim',
    },
    config = function()
        local mason_null_ls = require('mason-null-ls')

        local null_ls = require('null-ls')

        local null_ls_utils = require('null-ls.utils')

        mason_null_ls.setup({
            ensure_installed = {
                'prettier', -- prettier formatter
                'biome', -- js formatter
                'clang-format', -- c/c++ formatter
                'stylua', -- lua formatter
                'black', -- python formatter
                'pylint', -- python linter
                -- "eslint_d", -- js linter
            },
        })

        -- for conciseness
        local formatting = null_ls.builtins.formatting -- to setup formatters
        local diagnostics = null_ls.builtins.diagnostics -- to setup linters

        -- to setup format on save
        local augroup = vim.api.nvim_create_augroup('LspFormatting', {})

        -- configure null_ls
        null_ls.setup({
            root_dir = null_ls_utils.root_pattern('.null-ls-root', 'Makefile', '.git', 'package.json'),
            sources = {
                formatting.prettier, -- js/ts formatter
                formatting.stylua, -- lua formatter
                formatting.isort,
                formatting.black,
                formatting.clang_format,
                diagnostics.pylint,
                -- diagnostics.eslint_d.with({ -- js/ts linter
                --   condition = function(utils)
                --     return utils.root_has_file({ ".eslintrc.js", ".eslintrc.cjs" }) -- only enable if root has .eslintrc.js or .eslintrc.cjs
                --   end,
                -- }),
            },
            -- configure format on save
            on_attach = function(current_client, bufnr)
                if current_client.supports_method('textDocument/formatting') then
                    vim.api.nvim_clear_autocmds({ group = augroup, buffer = bufnr })
                    vim.api.nvim_create_autocmd('BufWritePre', {
                        group = augroup,
                        buffer = bufnr,
                        callback = function()
                            vim.lsp.buf.format({
                                filter = function(client)
                                    --  only use null-ls for formatting instead of lsp server
                                    return client.name == 'null-ls'
                                end,
                                bufnr = bufnr,
                            })
                        end,
                    })
                end
            end,
        })
    end,
}