Computer will not open Seamly2D

I am having issues with my MAC allowing Seamly2D to open. I keep getting a warning message saying “Seamly2D” cannot be opened because the developer cannot be verified. macOS cannot verify that this app is free from malware.

I am new to Seamly2D and would like to begin drafting my own patterns but this is becoming very frustrating. Has anyone else had similar issues or know how to fix this?

Thank you!


Hi, here is a copy and paste of my same problem. I have an older MacBook Air running an updated OS to “High Sierra” v10.13.3. I was able to download and run Seamly2D. It is considered an app and I was warned that it was not downloaded from an “identified developer.” In the System Preferences/Security, I told the Mac to open it anyways. And it did, no problem.


If you find Seamly2D in the finder window and right click on it, you will get an option to Open the file. It will say it’s not trusted and can’t be opened [the application is not signed by the developers], and will offer options of Cancel or Delete. Hit Cancel. Open it a second time in the same way and you’'l get three options, Open, Cancel and Delete. Open will work this time.

You only have to do this ONCE as when OSX knows the application can be trusted it will always open it.


Thank you! I was able to get Seamly2D to open with your help!


Thank you!!! I appreciate the help! It worked!