Addons are available as shown below:

Calendar

$14.99

Per year (Add-ons subject to yearly license for support and updates.)
Calendar can help to schedule tasks to gain control over your work. The use of task calendar is the main reason that keeps your day organized and supercharge your level of productivity.

Custom Fields

$19.99

Per year (Add-ons subject to yearly license for support and updates.)
Custom Fields extension allow you to collect extra information for your tasks. The Custom Fields extension is a very important tool for gathering accurate details on all your tasks.

Time Tracker

$19.99

Per year (Add-ons subject to yearly license for support and updates.)
Time Tracker add-on will help you to record and track the time spent on each individual task. We have designed this like a stop-watch for a task so that you can calculate the time spent on perticular task.

Gantt Chart

$19.99

Per year (Add-ons subject to yearly license for support and updates.)
Gantt Chart add-on effectively time manage your tasks and visualize upcoming deadlines for any project. Projects planners also use Gantt charts to maintain a bird's eye view of projects.

Duplicate Project

$19.99

Per year (Add-ons subject to yearly license for support and updates.)
Duplicate Project extention allows you to clone existing project and you will get same project with(tasks+checklists).