WGS 1984 Geoid - ESRI:105700

WKT

VERTCS["WGS_1984_Geoid", 
	VDATUM["WGS_1984_Geoid"], 
	PARAMETER["Vertical_Shift", 0.0], 
	PARAMETER["Direction", 1.0], 
	UNIT["Meter", 1.0]]

WKT2

VERTCRS["WGS_1984_Geoid", 
	VDATUM["WGS_1984_Geoid"], 
	CS[vertical, 1], 
	AXIS["Gravity-related height (H)", up, 
		LENGTHUNIT["Meter", 1.0]], 
	ID["Esri", "105700"]]

Data from @esri/proj-codes

{
  "wkid": 105700,
  "latestWkid": 105700,
  "macro": "PE_VCS_WGS_1984_GEOID",
  "name": "WGS_1984_Geoid",
  "wkt": "VERTCS[\"WGS_1984_Geoid\",VDATUM[\"WGS_1984_Geoid\"],PARAMETER[\"Vertical_Shift\",0.0],PARAMETER[\"Direction\",1.0],UNIT[\"Meter\",1.0]]",
  "wkt2": "VERTCRS[\"WGS_1984_Geoid\",VDATUM[\"WGS_1984_Geoid\"],CS[vertical,1],AXIS[\"Gravity-related height (H)\",up,LENGTHUNIT[\"Meter\",1.0]],ID[\"Esri\",\"105700\"]]",
  "description": "WGS 1984 Geoid",
  "authority": "Esri",
  "version": "9.3.0.0",
  "deprecated": "no",
  "areaname": "World",
  "extent": {
    "slat": -90,
    "nlat": 90,
    "llon": -180,
    "rlon": 180
  }
}