It's only the dreamers who ever move mountains.

Mirror Networking

The #1 free open source game networking library for Unity 2019 / 2020 / 2021 / 2022 LTS.

Used in production by major hits like Population: ONE and many more.

Originally based on UNET: battle tested since 2014 for 9 years and counting!

Mirror is stable, modular & easy to use for all types of games, even small MMORPGs 🎮.

Made in 🇩🇪🇺🇸🇬🇧🇸🇬🇹🇼 with ❤️.

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Features

Mirror comes with a wide variety of features to support all game genres.
Many of our features quickly became the norm across all Unity netcodes!

Feature	Description	Status
🎛 Transports	UDP, TCP, Websockets, Steam, Relay and more.	Stable
🪜 Interest Management	Spatial Hashing & Distance Checker to partition the world.	Stable
↗️ SyncDirection	Server & Client Authority - per component with one click.	Stable
🐌 Latency Simulation	Simulate latency, packet loss & jitter locally.	Stable
🧲 Batching	Minimize message overhead via batching automatically.	Stable
💌 RPCs & SyncVars	Synced vars and remote function calls built in & safe.	Stable
🙅‍♀️Allocation Free	Free of runtime allocations and no GC (except Transports).	Stable
🛞 Transform & Physics	Transform & Physics sync built in.	Stable
👩‍🍼 Child Components	Put networked components on anything.	Stable
🪚️ IL Post Processing	Zero overhead [Rpcs] and [Commands] via IL post processing!	Stable
☁️ Two Click Hosting	(Optional) Build & Push directly from Unity Editor to the Cloud.	Preview
📏 Snapshot Interp.	Perfectly smooth movement for all platforms and all games.	Stable
🏎 Fast Prediction	Simulate Physics locally & apply server corrections [VR ready]	Beta
🔫 Lag Compensation	Roll back state to see what the player saw during input.	Beta
🧙‍♂️ General Purpose	Mirror supports all genres for all your games!
🧘‍♀️ Stable API	Long term (10 years) stability instead of new versions!
🔬 Battle Tested	Mirror servers over 100 million players. It just works!
💴 Free & Open Source	MIT licensed without any restrictions to minimize risk!
❤️ Community	Join our Discord with nearly 15.000 developers world wide!
🧜🏻‍♀️ Long Term Support	Maintained since 2014 with optional LTS version!
🔒 Encryption	Secure communication with end-to-end encryption.	Preview
📐 Bitpacking	Optimized compression (bools as 1 bit etc.)	Researching

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Architecture

The Server & Client are ONE project in order to achieve maximum productivity.

Simply use NetworkBehaviour instead of MonoBehaviour.

Making multiplayer games this way is fun & easy:

public class Player : NetworkBehaviour
{
    // Synced automatically
    [SyncVar] public int health = 100;
    
    // Lists, Dictionaries, Sets too
    SyncList<Item> inventory = new SyncList<Item>();
    
    // Server/Client-only code
    [Server] void LevelUp() {}
    [Client] void Animate() {}
    
    void Update()
    {
        // isServer/isClient for runtime checks
        if (isServer) Heal();
        if (isClient) Move();
    }
    
    // Zero overhead remote calls
    [Command]   void CmdUseItem(int slot) {} // Client to Server
    [ClientRpc] void RpcRespawn() {}         // Server to all Clients
    [TargetRpc] void Hello() {}              // Server to one Client
}

There's also NetworkServer & NetworkClient. And that's about it 🤩

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Free, Open Source & Community Focused

Mirror is free & open source (MIT Licensed).

🍺 "Free" as in free beer, and freedom to use it any way you like.

• Host Game Servers anywhere!
• Customize anything freely!
• No paywalls, no CCU costs, no strings attached!

🤝 We are a team of professional game developers, who are paid to use Mirror in production. Our incentives will always align with the community, because we are Mirror users just like you!

❤️ Our fantastic community of over 14,000 users contributes feedback & improvements every day. Please join us on our journey, help others, and consider a Donation if you love our work!

The top quote is from Fitzcarraldo, which is quite reminiscent of this project.

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Getting Started

Get Unity 2019 / 2020 / 2021 / 2022 LTS, Download Mirror, 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.

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Mirror LTS (Long Term Support)

Mirror LTS is available on the Asset Store.

Mirror LTS gives you peace of mind to run your game in production. Without any breaking changes, ever!

• Bug fixes only.
• Consistent API: update any time, without any breaking features.
• Lives along side Unity 2019/2020/2021 LTS.
• Supported for two years at a time.

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Made with Mirror

Population: ONE

The BigBoxVR team started using Mirror in February 2019 for what eventually became one of the most popular Oculus Rift games.

In addition to 24/7 support from the Mirror team, BigBoxVR also hired one of our engineers.

Population: ONE was acquired by Meta in June 2021, and they've just released a new Sandbox addon in 2022!

Zooba

Wildlife Studio's hit Zooba made it to rank #5 of the largest battle royal shooters in the U.S. mobile market.

The game has over 100 million downloads on Google Play, with Wildlife Studios as one of the top 10 largest mobile gaming companies in the world.

Swarm VR

SPIDER-MAN WITH GUNS!

SWARM is a fast-paced, arcade-style grapple shooter, with quick sessions, bright colorful worlds and globally competitive leaderboards that will take you back to the glory days of Arcade Games.

Available for the Meta Quest, made with Mirror.

Castaways

Castaways is a sandbox game where you are castaway to a small remote island where you must work with others to survive and build a thriving new civilization.

Castaway runs in the Browser, thanks to Mirror's WebGL support.

Nimoyd

Nudge Nudge Games' first title: the colorful, post-apocalyptic open world sandbox game Nimoyd is being developed with Mirror.

Soon to be released for PC & mobile!

Unleashed

From original devs of World of Warcraft, Kingdoms of Amalur, and EverQuest comes a new family friendly fantasy adventure. Fight against the forces of darkness, explore a world consumed by wild magic, and build a stronghold with your friends to increase your power in a new world.

Lead by industry veterans Brian Birmingham & Irena Pereira, Unleashed is developing their next gen adventure game made with Mirror!

Follow them on X: https://twitter.com/UnleashingGames/

Dinkum

Set in the Australian Outback, Dinkum is a relaxing farming & survival game. Made by just one developer, Dinkum already reached 1000+ "Overwhelmingly Positive" reviews 1 week after its early access release.

James Bendon initially made the game with UNET, and then switched to Mirror in 2019.

A Glimpse of Luna

A Glimpse of Luna - a tactical multiplayer card battle game with the most beautiful concept art & soundtrack.

Made with Mirror by two brothers with no prior game development experience.

Havoc

Havoc is a tactical team-based first-person shooter with a fully destructible environment and a unique art style. Havoc has been one of our favorite made-with-Mirror games for a few years now, and we are excited to finally see it up there on Steam.

Sun Haven

Sun Haven - A beautiful human town, a hidden elven village, and a monster city filled with farming, magic, dragons, and adventure.

After their successful Kickstarter, Sun Haven was released on Steam in 2021 and later on ported to Mirror in 2022.

A Township Tale

A Township Tale is an immersive VR experience, where you can build towns and explore worlds with your friends.

Made with our KCP transport, available on the Meta Quest Store with over 6000+ ratings.

Inferna

One of the first MMORPGs made with Mirror, released in 2019.

An open world experience with over 1000 CCU during its peak, spread across multiple server instances.

Samutale

A sandbox survival samurai MMORPG, originally released in September 2016.

Later on, the Netherlands based Maple Media switched their netcode to Mirror.

Another Dungeon

Pixel Art Dungeon MMORPG reaching 5000 CCU at peak times.

Originally developed as a single-player idle game, it underwent a transition to an MMORPG three months before release thanks to Mirror!

Untamed Isles

The turn based, monster taming MMORPG Untamed Isles is currently being developed by Phat Loot Studios.

After their successful Kickstarter, the New Zealand based studio is aiming for a 2022 release date.

Portals

Animal Crossing meets Yakuza meets Minecraft — a city builder with a multiplayer central hub. Gather, trade and build — all in the browser!

SCP: Secret Laboratory

Northwood Studios' first title: the multiplayer horror game SCP: Secret Laboratory was one of Mirror's early adopters.

Released in December 2017, today it has more than 140,000 reviews on Steam.

Naïca Online

Naïca is a beautiful, free to play 2D pixel art MMORPG.

The France based team was one of Mirror's early adopters, releasing their first public beta in November 2020.

Laurum Online

Laurum Online - a 2D retro mobile MMORPG with over 500,000 downloads on Google Play.

Empires Mobile

Empires Mobile - Retro mobile MMORPG for Android and iOS, reaching 5000 CCU at times. Check out their video for some early MMORPG nostalgia.

Overpowered

Overwpowered, the exciting new card game that combines strategy, myth, and fun into one riveting web-based experience. Launched in 2023, made with Mirror!

And many more...

Modular Transports

Mirror uses KCP (reliable UDP) by default, but you may use any of our community transports for low level packet sending:

• (built in) KCP: reliable UDP
• (built in) Telepathy: TCP
• (built in) Websockets: Websockets
• Ignorance: ENET UDP
• LiteNetLib UDP
• FizzySteam: SteamNetwork
• FizzyFacepunch: SteamNetwork
• Epic Relay: Epic Online Services
• Bubble: Apple GameCenter
• Light Reflective Mirror: Self-Hosted Relay
• Oculus P2P: Oculus Platform Service

Benchmarks

• [2022] mischa 400-800 CCU tests
• [2021] Jesus' Benchmarks
• [2019] uMMORPG 480 CCU (worst case)

Development & Contributing

Mirror is used in production by everything from small indie projects to million dollar funded games that will run for a decade or more.

We prefer to work slow & thoroughly in order to not break everyone's games 🐌.

Therefore, we need to KISS 😗.

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Information Security

Mirror-Networking follows common information security industry standards & best practices.

Mirror is free open source software (MIT Licensed), with over 80% test coverage. The company is located in Germany. We do not collect any user data, impose no restrictions on users & developers, or rely on any closed source dependencies other than Unity.

This makes Mirror an attractive choice for government agencies and large corporations with strict information security requirements.

Feel free to reach out to business [at] mirror-networking.com if you have any questions, or need to review any of our policies:

• Development best Practices and SDLC.pdf
• Disaster Recovery Procedure.pdf
• Document Retention and Destruction Policy.pdf
• Encryption Policy.pdf
• Information Security Guidelines.pdf
• Privacy Policy
• Security Policy
• Vulnerability Management Policy.pdf

Please reach out if you decide to use Mirror.

We are excited to hear about your project, and happy to help if needed!

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Incident Response & Bug Bounty

A lot of projects use Mirror in production. If you found a critical bug / exploit in Mirror core, please follow the steps outlined in our Security Policy.

Credits / past findings / fixes:

• 2020, fholm: fuzzing ConnectMessage to stop further connects [#2397]
• 2023-04-05: IncludeSec: kcp2k UDP spoofing [#3286]
• 2023-06-27: James Frowen: ClientToServer [SyncVar] allocation attacks

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Credits & Thanks 🙏

🪞 Alexey Abramychev (UNET)
🪞 Alan
🪞 c6burns
🪞 Coburn
🪞 cooper
🪞 FakeByte
🪞 fholm
🪞 Gabe (BigBoxVR)
🪞 imer
🪞 James Frowen
🪞 JesusLuvsYooh
🪞 Mischa
🪞 Mr. Gadget
🪞 NinjaKickja
🪞 Paul Pacheco
🪞 Sean Riley (UNET)