lila

# [lichess.org](https://lichess.org)

[![Crowdin](https://d322cqt584bo4o.cloudfront.net/lichess/localized.svg)](https://crowdin.com/project/lichess)
[![Mastodon](https://img.shields.io/mastodon/follow/109298525492334687?domain=mastodon.online)](https://mastodon.online/@lichess)
[![Bluesky](https://img.shields.io/badge/Bluesky-0285FF?logo=bluesky&logoColor=fff)](https://bsky.app/profile/lichess.org)
[![Discord](https://img.shields.io/discord/280713822073913354?label=Discord&logo=discord&style=flat)](https://discord.gg/lichess)
[![Ask DeepWiki](https://deepwiki.com/badge.svg)](https://deepwiki.com/lichess-org/lila)

<img src="https://raw.githubusercontent.com/lichess-org/lila/master/public/images/home-bicolor.png" alt="Lichess homepage" title="Lichess comes with light and dark theme, this screenshot shows both." />

Lila (li[chess in sca]la) is a free online chess game server focused on [realtime](https://lichess.org/games) gameplay and ease of use.

It features a [search engine](https://lichess.org/games/search),
[computer analysis](https://lichess.org/ief49lif) distributed with [fishnet](https://github.com/lichess-org/fishnet),
[tournaments](https://lichess.org/tournament),
[simuls](https://lichess.org/simul),
[forums](https://lichess.org/forum),
[teams](https://lichess.org/team),
[tactic trainer](https://lichess.org/training),
a [mobile app](https://lichess.org/app),
and a [shared analysis board](https://lichess.org/study).
The UI is available in more than [140 languages](https://crowdin.com/project/lichess) thanks to the community.

Lichess is written in [Scala 3](https://www.scala-lang.org/),
and relies on a modified [Play 2.8](https://www.playframework.com/) framework.
[scalatags](https://com-lihaoyi.github.io/scalatags/) is used for templating.
Pure chess logic is contained in the [scalachess](https://github.com/lichess-org/scalachess) submodule.
The server is fully asynchronous, making heavy use of Scala Futures and [Pekko streams](https://pekko.apache.org).
WebSocket connections are handled by a [separate server](https://github.com/lichess-org/lila-ws) that communicates using [redis](https://redis.io/).
Lichess talks to [Stockfish](https://stockfishchess.org/) deployed in an [AI cluster](https://github.com/lichess-org/fishnet) of donated servers.
It uses [MongoDB](https://www.mongodb.com) to store more than 12 billion games, which are indexed by [elasticsearch](https://github.com/elastic/elasticsearch).
HTTP requests and WebSocket connections can be proxied by [nginx](https://nginx.org).
The web client is written in [TypeScript](https://www.typescriptlang.org/) and [snabbdom](https://github.com/snabbdom/snabbdom), using [Sass](https://sass-lang.com/) to generate CSS.
All rated games are published in a [free PGN database](https://database.lichess.org).
Browser testing done with [Browserstack](https://www.browserstack.com).
Proxy detection done with [IP2Proxy database](https://www.ip2location.com/database/ip2proxy).
Software builds and CI/CD