I want to find out the competition i have when i am starting up a blog. Is there any search engine or specific tool i can use to find other blogs on the same niche as mine?
Search the blog directories and use Google. Just type in NICHE blog. (Example: Marketing Blog) Your biggest competitors will usually have top rankings in Google.
A google search for the keyword is pretty much the best way to go, THEY are your compeititors because they rank well... there may be 1000s of other competitors but they dont rank so you dont need to worry about them.
Don't just focus on blogs, you should look at your keyword competitors on the whole. People usually want information not "a blog". They don't care if your a blog or a static site unless your niche has a strong sense of community.
sumply type your keyword on google. if the list shows that youre in the top, then you certainly beat your competitors