Anyone who wants to read Quran Al Kareem online, can go to several sites; many of which have many errors, are unreliable or are wrongly translated. But there are two exceptionally good and user friendly websites: Tanzil.info and Quran.com. Both are easy to access, have translations by several renowned Muslim scholars, in several languages and have varying transliterations.
The Holly Quran, is best and most fulfilling if read and understood in its original Arabic form. But, with millions of Muslims not understanding Arabic and as there are many non-Muslims wanting to understand the Holly Book, these two sites are two of a very few of the best and most reliable online sources available now; for reading and knowing Quran Al Kareem.