Shapefile loader in pgAdmin 4

Another option (for MacOS) is to download the Opengeo Suite 4.8 from here http://mac.softpedia.com/get/Developer-Tools/OpenGeo-Suite.shtml.

Then only pull the PostGIS Utilities to your applications folder. You can then delete the pgAdminIII App and just use the pgShapeLoader. Works with pgAdmin4 too.
After that, follow instructions from this Boundless tutorial:
http://postgis.net/workshops/postgis-intro/loading_data.html

I don't know if or how this is working for Windows.
I am running postgres 10.4 with pgAdmin4 on MacOS 10.13.

The other answers on this question so far doesn't cover the linux case. So, for linux users and in general for all other platforms, we can use QGIS to import shapefile to PostGIS or anyother spatial database.

Open QGIS, In top navigation bar, choose Database from the menu, select DB Manager.

Simply, connect to your database and choose import Layer/file option to import shapefile to database

original answer can be found here

I use pg Admin 4 and I have got the shapefile DBF loader that works perfectly and I access it through the start menu. Whereas with pg Admin 3 it is under plugin on the GUI but not with pg admin 4. pg Admin 4 is not trash, it is perfect and works perfectly. I use both 3 and 4. Please ensure that you install the software correctly with all the necessary tools.

I had the same problem and used the shp2pgsql-gui.exe that you can find at C:Program FilesPostgreSQL9.6binpostgisgui, it works fine.