This is my 6th of 7th post on this and I feel like I need to keep telling people this (especially from people where hijab is always associated with virginity and piety (so Pakistan, Afghanistan, Saudi, and Yemen)).
Conservative Muslims usually argue the evidence for hijab from the Quran, because there isn't any reliable hadith material that advocates for hijab. They try and break down the Arabic words to prove head covering is there, because the fact is Allah never flat out directly says "cover your hair". That is why these conservatives go through so much work and hastle to show hair covering is there. However, there are a significant amount of websites and videos that show there is nothing about head covering in the Quran, and they also break down the Arabic root and plural words.
The following are Quran-alone websites. I have not linked to them before, as the ten or twelve sources on my other posts about hijab not being mandatory are all from non-hadith rejecting websites. I feel like a change is needed for people to realize hijab is just not in the Quran, and I will use Quranist websites for this post. To some it might seem more clear. Even if you do not reject hadiths, still see the arguments in the websites and see the evidence against covering the head. If you wear a hijab, or support the view it is mandatory, you need to accept the fact that you know what? The argument of it being not mandatory is pretty solid and holds weight, whether you like it or not.
So anyways here they are:
http://www.quransmessage.com/articles/hijaab%20FM3.htm (surprisingly, this one is a little conservative. It still says head covering is not required, but it might be if women beautify themselves a way which causes attraction. I have to disagree with this because as I have mentioned before, hair cannot cause sexual arousal in men. The site also goes on to say arms and shoulders need to be covered. However, I disagree with this part also. Shoulders and arms do not cause sexual arousal either).
http://www.quranaloneislam.net/women-s-dress-code (very lengthy and detailed)
http://www.quranicpath.com/misconceptions/hijab_niqab.html (interesting as it uses science to prove its point).
A few points I want to make: Hair is not a sexual organ. It is not a vagina or breasts. So we need to stop treating it like a sexual part. As for arms, it makes no sense how that is sexualized. If a woman rolls up her sleeves to do a task, is she now sinning? It makes no sense.
Conservative Muslims say hijab is necessary because a woman's beauty needs to be covered. If a Muslim woman is beautiful, so be it. Get over it and move on. It is stupid to tell women to dress up because others might find her attractive. It is stupid to make women self conscious that she is attracting attention of males. It is stupid to call men "cucks" if their wives or sisters don't wear hijab (a sick game played by psychotic Muslims these days).
Islam says to be modest. Modesty varies from culture and place. What was modest in 7th century desert Arabia was to fit the norms at the time. Muslims, especially conservative Muslim men, need to realize this.