How to Make a To-Do List App Like Google Tasks or Todoist

The days of using a post-it note to remind yourself of a task or an upcoming event are long gone. It's been more than 30 years since the first productivity software was introduced.
To-do list apps are now a popular way to keep track of daily tasks and processes.
By 2021, the productivity software market will have generated $106.8 billion in revenue.