I was using App Game Kit (Studio) and it does support JSON. To import the exported tilemaps it took not very long. If your engine supports basic Sprite- and Image- handling and does understand JSON type structures it could be done in minutes or some hours, but less than half a day. Depends what your needs are.
Basic: Source code in App Game Kit for loading the map:
Type TileKit_JSON_Type
map as TileKit_Map_Type
EndType
Type TileKit_Map_Type
tile_w as integer
tile_h as integer
tile_spacing as integer
image_filename as string // name of the texture-atlas
animations as TileKit_Animation_Type[]
tags as string[]
w as integer
h as integer
data as integer[] // most important contains ids of the tiles from the texture-atlas
objects as TileKit_Object_Type[]
EndType
Type TileKit_Object_Type
name as string
id as string
x as integer
y as integer
w as integer
h as integer
color as string
EndType
Type TileKit_Animation_Type
idx as integer
rate as integer
frames as integer[] // array of index-ids of the tile-texture-atlas
EndType
// ------------------------- Function to load that Type into your engine itself -----
Function xb_LoadTileKit_JSON(name$)
tk_map as TileKit_JSON_Type
file = OpenToRead(name$)
json$ = ReadLine(file)
CloseFile(file)
tk_map.FromJSON(json$)
EndFunction tk_map