Apterous is a Countdown website maintained by Series 59 contestant Charlie Reams. It is the first site ever to allow players to play simulated games of Countdown online without the aid of MSN Messenger. The last 20 series champions are members. Apterous was accessible exclusively through a Java applet until April 2016, when the ability to play the game directly within one's browser was introduced.
Apterous was established on 29 June 2008; originally known as Netdown, it received its final name on 23 July. The site's second member, after Charlie Reams, was Jon O'Neill, who seems to have inspired the name of the site as it was a word he declared in his Championship of Champions XII preliminary.
Players log in and can play against other online players or the site robots ('bots'). The bots include 'Apterous Prune', 'Apterous Nude', 'Apterous Waldorf', 'Apterous Caesar', 'Apterous Plum', 'Apterous Velvet', 'Apterous Sponge', 'Apterous Prime' and 'Apterous Rex', each with their own skill level and other quirks. Players of Apterous are known as Apterites.
The site includes other forms of Countdown including Speed Countdown, Goatdown and Hypercountdown. The site automatically keeps count of a player's wins and losses, as well as the highest scores and highest ratings.
The Countdown Database is part of the website, and contains comprehensive records of over 5,000 games of televised Countdown as well as other series stats and stats on Octochamps. Since 2010, the Countdown Wiki has also been hosted exclusively on its servers at wiki.apterous.org.