At the same time you are thinking about an idea for your niche website, you should start thinking about domain names. Idea generation and domain names go hand in hand. The reason is because a lot of good domain names have already been taken either as active websites or by squatters who hope to resell them. It is very frustrating to have a good idea and a good idea on some branding concepts to find out someone else already had the same idea and has a website.
Finding a competitor, this doesn’t mean you can’t develop a niche website on the same topic. It just means you need to get more creative on your domain name. This might be adding an additional word to your domain name. But think of this as a creative branding exercise because you have flexibility in your domain name.
Part of picking a domain name, is deciding on a top-level domain like “.com”. If possible, go with a “.com” just to make it easier but there are many new top-level domain names now available. One might fit your niche website idea so definitely look at them.
Finally, think about the domain name you may select if it will cause confusion between existing websites that will be your competitor. For example, if a competitor has a domain with a “.com” and you select one with a different top-level domain name, this will just confusion your audience and might even drive traffic to your competitor due to the similarities. Unique domain names help with this.