If you need text properties based automation, pywinauto should help you. But there is no popular text-based cross-platform tool in Open Source field.

On macOs pyatom/ATOMac is good enough if you prefer Python (it requires some compilation during setup, but works well).

This is the big list of open source tools I'm maintaining.

• PyAutoGUI has image recognition capabilities (like Sikuli or Lackey) but it's not text based (even no Win32 API support).
• PyAutoIt bindings and AutoIt itself doesn't support MS UI Automation technology (only Win32 API).
• The Getting Started Guide for pywinauto explains some differences between these 2 technologies and how to switch between them in pywinauto.

Anyway this field is complicated and you may face many challenges. Feel free to ask more detailed questions because this question is more suitable for
Software Recommendations StackExchange site.

For Windows only GUI automation pywinauto is a bit more full-featured (and pythonic). It waits some default time implicitly and allows explicit waiting (some CPU-non-intensive loop is inside: kind of 0.1 sec pause and quick check for changes, then waiting again).

PyAutoGUI locateOnScreen function uses advanced analysis of the screenshot. That is why it's so CPU intensive (but cross-platform).

pywinauto example:

from pywinauto import Application

app = Application(backend="win32").start(u'your_app.exe')
app.MainWindow.menu_select(u'File->Open')

app.OpenDialog.Edit.set_edit_text(u'some path')
app.OpenDialog.Open.click()
app.OpenDialog.wait_not('visible', timeout=10)

new_main_window = app.window(title_re='^.* - The Software$')
new_main_window.wait('ready', timeout=15)

Getting Started Guide is a good starting point for learning pywinauto core concept.

Selenium is an industry standard for web GUI. But desktop GUI automation is almost an untilled field. There are several disparate tools that are able to deal with few types of GUI. I know only one cross-platform open source project for GUI testing based on accessibility technologies (therefore text-based): it's LDTP. But in my mind the interface is really ugly. That's why LDTP is not so popular.

Really nice tools are not cross-platform. One of the docs point to some of them.

Python tools

• pywinauto (https://github.com/pywinauto/pywinauto) is a very pythonic tool but it can manipulate only native GUIs on Windows (UI Automation API support is on the way)
• PyAutoGui (https://github.com/asweigart/pyautogui) - it’s a cross-platform but there is no windows/controls manipulation at all.
• AXUI (https://github.com/xcgspring/AXUI) - this is one of the wrappers around UI Automation API.

• winGuiAuto (http://www.brunningonline.net/simon/blog/archives/winGuiAuto.py.html) another module using Win32 API.

  Other scripting language tools

• Perl Win32::GuiTest (http://winguitest.sourceforge.net/)

• Ruby Win32-Autogui (https://github.com/robertwahler/win32-autogui)
• Ruby RAutomation (https://github.com/jarmo/RAutomation) - there are 3 adapters: Win32 API, UIA, AutoIt.
• C# Winium.Desktop (https://github.com/2gis/Winium.Desktop)

• others (http://www.opensourcetesting.org/functional.php)

  Other free tools

• AutoIt (http://www.autoitscript.com/)

• See collection at: https://github.com/atinfo/awesome-test-automation

Some tools use Machine Learning algorithms to find the elements on the screen by gold picture matching (Sikuli, PyAutoGUI), but they are still not reliable enough and can be chosen if you really need cross-platform solution or in some complicated cases where accessibility technologies are not available (GTK apps on Windows, for example).

P.S. I'm trying to keep some tools rating up-to-date if a popularity on GitHub/SO matters to you.