Is there a world generator App?

Many games like this, Valheim is one, have web apps that allow you to put in a kernal number and generate a map that lets you see if it is a suitable map. I have a server that has small main islands with huge water oceans between islands with the only way to cross these expanses is with a small rowboat or hours of swimming there is little use for players to visit or habitat. I want to change the map on my server but the need to rebuild and/or transfer everything is an obstacle. I dont want to choose another Dud for a map.