Anyone know about it?
Anyone know any tool which is good for content optimize such as readability checker, LSI keyword checker, etc.
For readability, no one is better than SEO Yoast readability functions. For LSI keywords I would recommend the manual re-check is better than nothing.
But SEO yoast is a wordpress plugin. how can i check normal website content?
What do you mean by the normal site? Are you talking about the custom developed site?If yes so please asked your developer to integrate all those SEO features in that or you can do it everything manually that is huge panic if there are innumerable web pages.