How to open .PLANNER file extension?

If you cannot open a new file that has been saved in the .PLANNER format you need to download the appropriate software. The manufacturer of .PLANNER files is The GNOME Project; .PLANNER files belong to the Data Files category. After downloading the application from the list available on our website just run an unknown file, and as the default set the newly installed application supporting the .PLANNER files. Activities performed in the order described should solve the problems with all the files in the .PLANNER format.

• What is .PLANNER file?
• How to open .PLANNER file?
• What is .PLANNER file?