Agar.io is a browser game, with the browser being the client that connects to a server.
Server[]
- The server is the owner of the "game world". The server has all the information about the game world and calculates all of its changes. The client does not directly manipulate anything in the game world. The client only sends requests / intents. For example, if the player pressed the split key, the client send a request to do a split to the server and then the server handles it. This is very common amongst multiplayer games.
- The client and the server follow a certain protocol when communicating with each other. This allows them to communicate efficiently.
- The client and the server use websockets to communicate.
Client[]
- The client is independent from the server. In the past, it was possible to connect different clients and servers. For example people setup private servers and connected to them with the regular Agar.io client. However, nowadays this is much more difficult.
- The client is written in HTML, CSS, and JavaScript.
- The source code cannot be read, because it has been obfuscated.
- It has not always been obfuscated, the earlier Agar.io versions have been used to create alternative clients.
- Data is sent to the server in packets that are following the protocol and are sent as binary.