Google Tasks Offline is a Chrome app that allows Chromebook and general Chrome users to use a cool offline task manager that syncs up with Google Tasks. It works both offline and online as a Google Task Client which is unaffiliated with Google.
Some of its great features are:
Hotkeys: For scrolling and editing
Autosyncing: All your actions are auto-synced to your Google Tasks.
Provides Subtasks: Works just like Google tasks, tab and untab to set the level.
Manual One Click Sync: You can press sync once only to force a sync manually.
Multiple List With Easy Management: You can create multiple to do list on the same page. Filter system on the lower left will allow you to concentrate on one list
Access Everything Without Active Connection: There is no need of internet connection to edit your tasks, you can do so offline and they will get synced next time you are connected to Internet.
How to use the Google Tasks Offline?
Install its Chrome Extension here, it will automatically adds a new bookmark on your Chrome’s App Page which when clicked directs you to the Offline Task Manager.