I want to use OSM in flutter .but I cannot add it to flutter and i want to use any free maps like this. I don't wanna pay for APIs .what should I do? Is there any way to add OSM To flutter. it takes couples of day and I can't add any map to my app!
You should use the flutter_map package, like quoci said in the comments.
It allows you to view maps from any source that gives a URL as an access method. There are plenty of setup instructions and examples on the package's readme page for you to get started.