GD-Link Adapter is a low coast emulator for GD32, you can buy for example form Special-Ind.
This emulator is compatible with the principal IDE (KEIL, IAR, etc).
The standalone sw (GD-Link Programmer) for programing, erasing, etc, the GD32 is here. The GD-Link Adapter User Manual is here.
NOTE:
All the GD32 Evaluation Boards and Starter Kits include the emulator directly on the boards.