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Stop worrying about networking. Because we do.


Mirror is a high level Networking library for Unity, compatible with different low level Transports.

Mirror is for small indie games & large scale MMOs, made by the developers of uMMORPG and Cubica.

Mirror is optimized for ease of use & probability of success.

We needed a networking library that allows us to launch our games and survive the next decade.


The Server & Client are ONE project in order to achieve an order of magnitude gain in productivity.

Making multiplayer games this way is fun & easy. Instead of MonoBehaviour, Mirror provides NetworkBehaviour components with:

  • [Server] / [Client] tags for server-only / client-only code
  • [Command] for Client->Server function calls (e.g. UseItem)
  • [ClientRpc] / [TargetRpc] for Server->Client function calls (e.g. AddChatMessage)
  • [SyncVar] / SyncList to automatically synchronize variables from Server->Client

Note: Mirror is based on Unity's abandoned UNET Networking system. We fixed it up and pushed it to MMO Scale.

Low Level Transports

Getting Started

Get Unity 2019 LTS, download Mirror on the Asset Store, open one of the examples & press Play!

Check out our Documentation to learn how it all works.

If you are migrating from UNET, then please check out our Migration Guide.

Made with Mirror

Population: ONE
Population: ONE


SCP: Secret Laboratory
SCP: Secret Laboratory

Naïca Online
Naïca Online

Laurum Online
Laurum Online

And many more...


Mirror is free & open source software funded by Donations. If you love it, please consider supporting Mirror on GitHub. As reward, you'll receive our Network Profiler, priority support and more :)


Development & Contributing

Mirror is used in production by games ranging from small indie projects to large scale MMOs that will run for a decade or more.

10 years from now if your players encounter a networking bug and most of our contributors already moved on, someone will need to fix it. Therefore it is of utmost importance for us to follow the KISS principle in order for our games to survive.

Keeping the next decade in mind, contributing fixes / tests / improvements is highly appreciated while new features have a low probability of being merged.

At this point, what we don't add to Mirror is more important than what we do add to it!

Bug Bounty

A lot of projects use Mirror in production. If you found a critical bug / exploit in Mirror core, please reach out to us in private. Depending on the severity of the exploit, we offer $50 - $500 for now. Rewards based on Mirror's donations, capped at amount of donations we received that month.

Specifically we are looking for:

  • Ways to crash a Mirror server
  • Ways to exploit a Mirror server
  • Ways to leave a Mirror server in undefined state

We are not looking for DOS/DDOS attacks. The exploit should be possible with just a couple of network packets, and it should be reproducible.

Credits / past findings / fixes:

  • 2020, fholm: fuzzing ConnectMessage to stop further connects [#2397]