that uses a
tag system for image categorization. e621 is a
furry-themed
booru-style
imageboard: a gallery in which "posts" (uploads encompassing images, videos, and
Adobe Flash files under the
SWF format prior to the format's discontinuation), largely
digital art images, are categorized with
tags. While e621 allows for both
safe for work and not safe for work content, furry pornography—known as
yiff—is the website's largest collection; it is also for what e621 is best known. In this way, users can utilize the tagging function to search for artwork containing particular
fetishes or
kinks. e621 also hosts other forms of artwork, such as
kemonomimi,
Pokémon, and ponies from the animated children's TV series
My Little Pony: Friendship Is Magic (the erotic art of which is known as
clop). Over 82,469 posts on e621 were tagged
My Little Pony by 2015; , the five most tagged characters on e621 are, in descending order, Twilight Sparkle with over 38,300 posts,
Judy Hopps from
Zootopia with over 37,600 posts,
Fluttershy with over 30,700 posts,
Rainbow Dash with over 29,600 posts, and
Nick Wilde with over 28,900 posts. On March 5, 2020, e621 released its source code under the terms of the
2-clause BSD license. The site is a heavily-modified fork of the
Danbooru anime-focused imageboard, and uses the
Ruby on Rails framework. As of January 2024, e621 had almost 4 million posts. The website also contains a
discussion forum and a
wiki for its tags, as well as a
safe for work (SFW)
mirror site called e926. As of February 2025,
AI-generated art or AI-assisted art is generally banned from being posted on e621 with exceptions for backgrounds, artwork that references, but does not directly use, AI-generated content, and for audio for video posts. AI-assisted and AI-generated content is now instead hosted on the sister site
e6ai.net. ==Website blocks==