Development of GNS3
Using the GNS3 API
http://api.gns3.net/en/latest/
Get the Source Code
At first you need to clone both project:
If you want to access to the code of next big release in both project:
For example:
Dependencies
Linux
If you are on Linux the best is to install GNS3 via the ppa. This will setup all the dependencies required for the development.
Go to both folder (gns3-gui & gns3-server)
Windows
On Windows you need to install Python 3.5 and PyQT. Go to both folder (gns3-gui & gns3-server)
Mac OS X
With homebrew:
Go to both folder (gns3-gui & gns3-server)
Run Tests
For Linux & Mac OS X
After that the tests should work go to both projects. And run:
For Windows
After that the tests should work go to both projects. And run:
Start the Server
For Linux & Mac OS X
Go to the gns3-server folder and run:
For Windows
Start the GUI
For starting the gui go to the gns3-gui folder.
For Linux & Mac OS X
For Windows
Modify the GUI
We will start by a simple modification by adding your name to the thanks to in the about dialog.
In the gns3-gui folder open with the Qt Designer the file gns3/ui/about_dialog.ui click on Thanks to and add your name to the list:

Click on About (otherwise the dialog will open the Thanks to tab) and save. Now you need to export the dialog to python code. Just run:
This will regenerate all the changed Qt interface. You can now start the GUI and see your change.
Contribute Code
You can create a pull request on Gui or Server via Github. Even for work in progress code. We will help you.