To play Assetto Corsa online you can use the server list in the original Steam launcher, although most players join from the Online tab in Content Manager, which filters servers, detects the content you’re missing and in many cases downloads it for you. To join, you need exactly the same car and track installed as the server, and often Custom Shaders Patch too. If you want to host your own server, the game includes the official dedicated server (acServer), which by default uses port 9600 on TCP and UDP and 8081 on TCP for HTTP.
How to join an Assetto Corsa server
From the original launcher
The Kunos launcher has a multiplayer section with the public server list. There are two session types: in booking sessions you have to sign up within the window set by the server, and in pickup sessions you choose an available car and join the session in progress. It’s enough for servers running official content, but it won’t help you find or download mods.
From Content Manager (recommended)
Content Manager is the alternative launcher used by almost the entire community. Its online mode lets you mark favorite servers, hide the ones you don’t care about, tag players and download the content you’re missing. It also integrates racing services like RSR Live Timing, Sim Racing System and World Sim Series. Besides searching the list, you can connect directly to a private server with its IP and port.
If the server uses the Content Manager add-on (Content Manager Wrapper) and its links are direct downloads, you’ll see a button to install the missing content. If not, the links usually appear in the server description and you’ll have to download and install the mods manually. If you’re not sure how, follow our guide to installing mods in Assetto Corsa.
Why you can’t join: content, checksums and CSP
- Different car or track version. The server compares your files with its own (checksums): by default, each car’s
data.acdfile and the track’s surface and configuration data. If you’re missing something or your version doesn’t match, the server kicks you. Install exactly the version the server specifies; for example, most Shutoko Revival Project servers require the stable version and its car pack. - Minimum CSP version. The admin can require a minimum Custom Shaders Patch version to join. Free-roam servers with traffic and dynamic weather, which usually run on AssettoServer, absolutely need CSP. Update it from Content Manager.
- Server full or misconfigured. If the server allows more players than the car slots defined, people can’t join even if free spots appear.
Well-known communities and servers
There are thousands of public servers, but these are the most common starting points:
- Low Fuel Motorsport (LFM): a racing platform with skill-based rankings. Since 2024 it has run Assetto Corsa races with in-game content and some paid mods from well-known studios, alongside other sims.
- Sim Racing System (SRS): free ranked races that match you with drivers of a similar level. It publishes each week’s track so you can practice beforehand. It’s integrated into Content Manager.
- RSR Live Timing and World Sim Series: also integrated into Content Manager, with leaderboards and events.
- Shutoko Revival Project servers: the project has its own servers for cruising the Tokyo expressways with its free car pack.
- Free-roam and traffic servers: open maps with AI traffic, very popular for cruising or drifting. They usually require CSP and specific content linked in the description.
Many leagues and race servers also use Real Penalty to apply automatic penalties for track limits or jump starts.
How to host your own Assetto Corsa server
Option 1: the official dedicated server
Kunos ships the server with the game. It’s in the server folder of the install (for example, steamapps\common\assettocorsa\server), with a graphical manager for Windows (acServerManager.exe). It’s also available as a separate Steam tool, «Assetto Corsa Dedicated Server» (app 302550), which you can download with SteamCMD on a Windows or Linux server; on Linux there’s only a 32-bit binary. The configuration is stored in two files in the cfg folder:
server_cfg.ini: name, password, admin password, track, sessions, ports, maximum players and rules such as fuel consumption, tire wear or damage.entry_list.ini: the list of slots, with each one’s car and livery.
If you use mods, the server also needs those cars and that track, because it needs them to check players’ files.
Option 2: Content Manager
Content Manager has a server section (menu in the top-right corner, Server option) where you create a preset, choose the track, set the capacity and add cars in the Entry List tab. From there you can launch it on your PC or pack it up and upload it via FTP to a rented server. According to guides from several hosting providers, this feature requires the full version of Content Manager, the one you get by donating to the author; the free Lite version doesn’t manage servers.
Option 3: alternative managers
- AssettoServer: a free, open-source alternative server (AGPL license) focused on free roam. It adds configurable AI traffic, dynamic weather with rain (requires CSP) and a plugin system.
- Assetto Corsa Server Manager: a web interface for managing servers, maintained by Emperor Servers, which offers it hosted or for installing on your own machine. Its old open-source GitHub repository is archived.
Assetto Corsa server ports
These are the default values in server_cfg.ini. You can change them, but what you open on your router has to match what you put in the file:
| Parameter | Default port | Protocol |
|---|---|---|
UDP_PORT |
9600 | UDP |
TCP_PORT |
9600 | TCP |
HTTP_PORT |
8081 | TCP |
So other players can find you:
- Forward those ports on your router to the local IP of the PC running the server.
- Allow
acServer.exethrough Windows Firewall. - Leave
REGISTER_TO_LOBBY=1so it shows up in the public list, and wait a minute or two after starting it. - Check that the maximum number of players (
MAX_CLIENTS) doesn’t exceed the slots defined inentry_list.ini. - After changing ports or content, fully restart the server: it loads the content at startup.
Frequently asked questions
Do I need Content Manager to play online?
It isn’t required: the original launcher has its own server list. But Content Manager makes it much easier to find servers, see what you’re missing and download it, and almost every modded server assumes you’re using it.
Why does the server kick me when I join?
The most common reason is a checksum failure: you have a different version of the car or track, or you’re missing a file. Download the exact version the server specifies. It may also require a minimum CSP version.
Why doesn’t my server show up in the list?
Check that REGISTER_TO_LOBBY is set to 1, that TCP and UDP port 9600 and port 8081 are open and forwarded to the right PC, and that the firewall allows acServer.exe. It takes a minute or two to appear.
Is playing Assetto Corsa online free?
Yes. There’s no subscription: public servers are free. Some servers or competitions use paid cars or tracks, and you will have to buy those if you want to join them.