WebTiles is the latest online tile-based interface for Dungeon Crawl Stone Soup, as well as the offshoot minigame Dungeon Sprint. It replaces the traditional Crawl ASCII presentation with tile graphics.
Webtiles is by and large the most popular way to play Crawl online; the 0.28 tournament saw 96.6% of players using Tiles. There is no need to for an SSH cilent, unlike console. Tiles are also generally seen as a useful way to introduce new players to the game, as images are much more intuitively informative than characters.
Once logged in, you may spectate on any ongoing game, and a basic chat feature allows you to communicate with the player and other spectators in real time. This makes it a great tool for giving advice to new players as they encounter dangerous situations (though general trolling is not unheard of). There is currently no way to play in a Private mode, apart from downloading the game and playing offline.
WebTiles is currently available on most offical servers. In general, playing on the server geographically closest to you will help reduce in-game lag, though heavy traffic can also be a major factor. These servers always host the latest stable release of Crawl, as well as the current trunk release and several of the more recent older versions.
Regardless of which server you play on, your play statistics will be recorded across all servers and can be viewed at http://crawl.akrasiac.org/scoring/players/YOUR ACCOUNT NAME.html. Because all saves are kept in cloud storage, you can log in from any computer to continue any of your ongoing games.