diff --git a/lua/navigate-note/conf.lua b/lua/navigate-note/conf.lua
index c56ede8..d0737d5 100644
--- a/lua/navigate-note/conf.lua
+++ b/lua/navigate-note/conf.lua
@@ -1,6 +1,20 @@
 local M = {
   options  = {},
   defaults = {
+    
+    keymap = {
+      nav_mode = {
+        next = "<tab>",
+        prev = "<s-tab>",
+        open = "<m-cr>",
+        switch_back = "<m-h>",
+        _tmp_ = {
+          append_link = "a",
+        },
+      },
+      add = "<localleader>na",
+      open_nav = "<m-h>",
+    },
   }
 }
 
diff --git a/lua/navigate-note/mappings.lua b/lua/navigate-note/mappings.lua
index 33a031a..2867b3e 100644
--- a/lua/navigate-note/mappings.lua
+++ b/lua/navigate-note/mappings.lua
@@ -1,7 +1,11 @@
 local M = {}
-
+local ops = require"navigate-note.ops"
+local options = require"navigate-note.conf".options
 
 function M.setup_main_mappings()
+  -- Key mappings
+  vim.keymap.set("n", options.keymap.add, ops.add_file_line, { noremap = true, silent = true })
+  vim.keymap.set("n", options.keymap.open_nav, ops.switch_nav_md, { noremap = true, silent = true })
 end
 
 
diff --git a/lua/navigate-note/ops.lua b/lua/navigate-note/ops.lua
new file mode 100644
index 0000000..b16c970
--- /dev/null
+++ b/lua/navigate-note/ops.lua
@@ -0,0 +1,306 @@
+--[[
+This is a vim plugin.
+
+When we enter a file named `nav.md`, it will switch into nav-mode in the buffer.
+You will navigate to the next `file:line` pattern in the `nav.md` when I press <tab>.
+When I press <enter> when I'm on `file:line`, enter the according file and line.
+It will leave the nav-mode if I leave the buffer.
+
+When I'm not in nav-mode, `<localleader>na` will add a new line `file:line` (i.e. the position of current file) into the file `nav.md`.
+
+`<localleader>nn` will open the `nav.md`.
+
+Here is an example of `nav.md`
+```markdown
+- `start.sh:30`:  the entrance of the project
+- `src/utils.py:40`: important utils
+```
+
+TODOs:
+- [ ] Append to next line
+- [ ] Always use relative path
+]]
+local options = require"navigate-note.conf".options
+
+local M = {
+  last_entry = "",
+  active_keymap = {},
+}
+
+local api = vim.api
+local nav_md_file = "nav.md"
+
+local file_line_pattern = "`([^:`]+):?(%d*)`"
+
+-- Function to return all {line_number, start_pos, end_pos} in appearing order
+local function get_all_matched(content)
+  if content == nil then
+    content = table.concat(api.nvim_buf_get_lines(0, 0, -1, false), "\n")
+  end
+
+  local matches = {}
+  local line_number = 1
+
+  -- Iterate through each line, including blank lines
+  for line in content:gmatch("([^\r\n]*)\r?\n?") do
+    local start_pos, end_pos = 0, 0
+    while true do
+      start_pos, end_pos = string.find(line, file_line_pattern, end_pos + 1)
+      if not start_pos then
+        break
+      end
+      table.insert(matches, { line_number, start_pos - 1, end_pos - 1 }) -- -1 to align with the (0, 1) based pos
+    end
+    line_number = line_number + 1
+  end
+
+  return matches
+end
+
+local function navigate_to_next(reverse)
+  local cursor_pos = api.nvim_win_get_cursor(0)
+
+  -- Get all matches in the current buffer
+  local buffer_content = table.concat(api.nvim_buf_get_lines(0, 0, -1, false), "\n")
+  local matches = get_all_matched(buffer_content)
+  if #matches == 0 then
+    print("No file:line patterns found")
+    return
+  end
+
+  local found = false
+  if reverse then
+    -- Find the previous match
+    for i = #matches, 1, -1 do
+      local match = matches[i]
+      if match[1] < cursor_pos[1] or match[1] == cursor_pos[1] and cursor_pos[2] > match[3] then
+        api.nvim_win_set_cursor(0, { match[1], match[2] })
+        found = true
+        break
+      end
+    end
+
+    if not found then
+      api.nvim_win_set_cursor(0, { matches[#matches][1], matches[#matches][2] })
+    end
+  else
+    -- Find the next match
+    for _, match in ipairs(matches) do
+      if match[1] > cursor_pos[1] or match[1] == cursor_pos[1] and cursor_pos[2] < match[2] then
+        api.nvim_win_set_cursor(0, { match[1], match[2] })
+        found = true
+        break
+      end
+    end
+
+    if not found then
+      api.nvim_win_set_cursor(0, { matches[1][1], matches[1][2] })
+    end
+  end
+end
+
+local function navigate_to_prev()
+  navigate_to_next(true)
+end
+
+-- Function to open the file and line under cursor
+local function open_file_line()
+  local current_line = api.nvim_get_current_line()
+  -- match pattern like `src/utils.py:40` or `src/utils.py`
+  local file, line = string.match(current_line, file_line_pattern)
+  if file then
+    P(file)
+    api.nvim_command("edit " .. file)
+    if line and line ~= "" then
+      api.nvim_win_set_cursor(0, { tonumber(line), 0 })
+    else
+      print("Opened file: " .. file .. " (no specific line number provided)")
+    end
+  else
+    print("No valid file:line pattern under cursor")
+  end
+end
+
+local function get_entry()
+  return string.format("`%s:%d`", vim.fn.expand("%"), vim.fn.line("."))
+end
+
+local function write_entry(entry)
+  if entry == nil then
+    entry = M.last_entry
+  end
+  -- Open nav.md and append the new entry
+  local buf_exists = false
+  local cur_buf = vim.api.nvim_get_current_buf()
+  local cur_buf_name = vim.fn.fnamemodify(vim.api.nvim_buf_get_name(cur_buf), ":p")
+  local nav_md_full_path = vim.fn.fnamemodify(nav_md_file, ":p")
+
+  if cur_buf_name == nav_md_full_path then
+    -- If the current buffer is nav.md, append the entry at the current cursor position
+    local cursor_pos = vim.api.nvim_win_get_cursor(0)
+    vim.api.nvim_buf_set_lines(cur_buf, cursor_pos[1], cursor_pos[1], false, { entry })
+    print("Added entry to nav.md buffer at cursor position: " .. entry)
+  else
+    for _, buf in ipairs(vim.api.nvim_list_bufs()) do
+      local buf_name = vim.fn.fnamemodify(vim.api.nvim_buf_get_name(buf), ":p")
+      if buf_name == nav_md_full_path then
+        buf_exists = true
+        break
+      end
+    end
+
+    if buf_exists then
+      -- If nav.md is already open in a buffer, update the buffer
+      local bufnr = vim.fn.bufnr(nav_md_file)
+      vim.api.nvim_buf_set_lines(bufnr, -1, -1, false, { entry })
+      print("Added entry to nav.md buffer: " .. entry)
+    else
+      -- Otherwise, append to the file
+      local f = io.open(nav_md_file, "a")
+      if f then
+        f:write(entry .. "\n")
+        f:close()
+        print("Added entry to nav.md: " .. entry)
+      else
+        print("Failed to open nav.md")
+      end
+    end
+  end
+end
+
+-- Function to add a new file:line entry to nav.md
+function M.add_file_line()
+  local entry = get_entry()
+  write_entry(entry)
+end
+
+-- Function to open nav.md
+function M.switch_nav_md()
+  M.last_entry = get_entry()
+  if vim.fn.expand("%:t") == "nav.md" then
+    -- If we are already in nav.md, go to the previous file by pressing "<C-^>"
+    vim.api.nvim_feedkeys(vim.api.nvim_replace_termcodes("<C-^>", true, false, true), "n", true)
+  else
+    vim.cmd("edit " .. nav_md_file)
+  end
+end
+
+local function onetime_keymap(key, func, callback)
+  local function _func()
+    vim.keymap.del("n", key, { noremap = true, silent = true, buffer = true })
+    M.active_keymap[key] = nil
+    func()
+    if callback ~= nil then
+      callback()
+    end
+  end
+  vim.keymap.set("n", key, _func, { noremap = true, silent = true, buffer = true })
+  M.active_keymap[key] = _func
+end
+
+local function render_winbar_text()
+  -- render all keymap in conf.keymap.nav_mode
+  -- only include active _tmp_ keymap in active_keymap and persistent key map
+  local title = "🎹:"
+
+  -- Include persistent keymaps
+  for name, key in pairs(options.keymap["nav_mode"]) do
+    if name ~= "_tmp_" then
+      title = title .. " " .. string.format("(%s)%s", key, name)
+    end
+  end
+
+  -- Include active temporary keymaps
+  for name, key in pairs(options.keymap["nav_mode"]._tmp_) do
+    for a_key, _ in pairs(M.active_keymap) do
+      if a_key == key then
+        title = title .. " " .. string.format("(%s)%s", key, name)
+      end
+    end
+  end
+
+  return title
+end
+
+local update_winbar_text = function()
+  vim.api.nvim_set_option_value("winbar", render_winbar_text(), { win = vim.api.nvim_get_current_win() })
+end
+
+local function open_ith_link(i)
+  local matches = get_all_matched()
+  if #matches < i then
+    print("No such link")
+    return
+  end
+  local match = matches[i]
+  api.nvim_win_set_cursor(0, { match[1], match[2] })
+  open_file_line()
+end
+
+local NAV_LINK_NS = vim.api.nvim_create_namespace('NavigationLink')
+
+local function update_extmark()
+  -- Clear previous extmarks before setting the new extmarks
+  local bufnr = vim.api.nvim_get_current_buf()
+  vim.api.nvim_buf_clear_namespace(bufnr, NAV_LINK_NS, 0, -1)
+
+  local matches = get_all_matched()
+  for i, match in ipairs(matches) do
+    if i > 9 then
+      break
+    end
+    vim.api.nvim_buf_set_extmark(bufnr, NAV_LINK_NS, match[1] - 1, match[3], {
+      virt_text = { { string.format("🎹[%d]", i), "Comment" } },
+      virt_text_pos = "inline",
+    })
+  end
+end
+
+-- Function to enter nav-mode
+local function enter_nav_mode()
+  update_extmark()
+  vim.keymap.set("n", options.keymap["nav_mode"].next, navigate_to_next, { noremap = true, silent = true, buffer = true })
+  vim.keymap.set("n", options.keymap["nav_mode"].prev, navigate_to_prev, { noremap = true, silent = true, buffer = true })
+  vim.keymap.set("n", options.keymap["nav_mode"].open, open_file_line, { noremap = true, silent = true, buffer = true })
+  vim.keymap.set("n", options.keymap["nav_mode"].switch_back, M.switch_nav_md, { noremap = true, silent = true, buffer = true })
+
+  if M.last_entry ~= "" then
+    onetime_keymap(options.keymap["nav_mode"]._tmp_.append_link, write_entry, update_winbar_text)
+  end
+  update_winbar_text()
+
+  -- Map 1, 2, 3, ..., 9 to open the i-th link in nav.md
+  for i = 1, 9 do
+    vim.keymap.set("n", tostring(i), function()
+      open_ith_link(i)
+    end, { noremap = true, silent = true, buffer = true })
+  end
+  print("Entered nav-mode")
+end
+
+-- Function to leave nav-mode
+local function leave_nav_mode()
+  print("Left nav-mode")
+end
+
+-- Autocommand to enter nav-mode when nav.md is opened
+local nav_mode_group = vim.api.nvim_create_augroup("NavMode", { clear = true })
+vim.api.nvim_create_autocmd("BufEnter", {
+  pattern = nav_md_file,
+  callback = enter_nav_mode,
+  group = nav_mode_group,
+})
+
+vim.api.nvim_create_autocmd("BufLeave", {
+  pattern = nav_md_file,
+  callback = leave_nav_mode,
+  group = nav_mode_group,
+})
+-- Autocommand to update extmarks when content changes
+vim.api.nvim_create_autocmd({"TextChanged", "TextChangedI", "TextChangedP"}, {
+  pattern = nav_md_file,
+  callback = update_extmark,
+  group = nav_mode_group,
+})
+
+return M