Humans of New York, a Facebook page that celebrates human voices and diversity, has taken a stand against Republican presidential candidate Donald Trump.

HONY's founder, Brandon Stanton, who has always remained behind the lens and known for being taciturn to allow the subjects of his photographs speak, has written an uncharacteristic open letter addressed to Trump.

The letter was posted on his page with more than 17 million followers.

In it, Stanton openly calls out Trump's antics, including his racism and hate speech, and said there is not a good time to oppose violence and prejudice as "(t)he time is always now".

In less than 45 minutes since the post went up, it has received close to 500,000 reactions: