EasyEDA provides a real time DRC(Design Rule Check) function.

Via at:Setting > Design Rule Setting to open the DRC setting dialog:

Note: When you convert a schematic to PCB, the real time DRC is open. But in the old PCB, the real time DRC is closed. you can open it as in the image above.

This is a big feature of EasyEDA. It is hard to fix DRC errors after laying out the PCB. Now EasyEDA will let you know the error in routing. You will find an X flag to mark the error, such as Track to Track or Track to PAD like in the image below