# Mirror: the Unity networking library that outlived UNET > MIT licensed, C#, and shipping date-stamped releases like v96.11.3, Mirror gives Unity developers RPCs, SyncVars, snapshot interpolation, and a choice of seven transports without a licensing tier. **MirrorNetworking/Mirror** — #1 Open Source Unity Networking Library - Repository: https://github.com/MirrorNetworking/Mirror - Website: https://mirror-networking.com - Stars: 6,356 · Forks: 872 - Language: C# - License: MIT - Published: 2026-10-08 · Updated: 2026-10-08 · Language: en - Canonical page: https://hysenlabs.com/projects/mirrornetworking-mirror ## A Unity library with a decade of production behind it Mirror describes itself as the number one free open source game networking library for Unity, and the repository description is blunter still, claiming the number one open source Unity networking library. The marketing adjectives are easy to discount, so it is worth looking at what is verifiable underneath. The README states the library is used by over 200 million players and powers major releases including Population: ONE along with over 1000 games on Steam, with a link to the SteamDB SDK page that would let you check that claim yourself. Those two numbers are self-reported by the project, so treat them as a claim rather than a measurement. What is harder to argue with is the date. The README says Mirror was originally based on UNET and has been battle tested since 2014, which works out to more than a decade of continuous maintenance. Unity's original UNET announcement is linked through the Wayback Machine, which is its own commentary on how that technology ended. The licensing is the other thing that distinguishes Mirror from the alternatives. It is MIT, with a LICENSE file at the repository root and a badge in the README, which means you can read the source, modify it, and ship it without buying seats or reporting revenue. There is a FUNDING.yml and a funding.json at the root, so the project accepts sponsorship, but nothing in the license gates your commercial use. Scale on the hosting side is solid: 6,337 stars, 871 forks, and 68 open issues, with the last push dated 2026-09-19 and nothing archived. The topic list is a good summary of the library's history and its ambitions at once, running from hlapi, kcp, libuv, tcp, udp, and unet on the old-Unity side through mirror, networking, telepathy, and unity on the current side, plus mmo, mmorpg, mmos, and ummorpg for the genre claims. Telepathy is a serialization library Mirror has long been associated with. The project also says where it was made, listing Germany, the United States, the United Kingdom, Singapore, and Taiwan, which is a reasonable indicator of the contributor base for a library this widely depended on. ## The badges still point at a repository that moved One detail in this README says more about the project's history than anything else: the badges and links at the top of the file still resolve to an organization that is no longer the home of the code. The license badge links to `vis2k/Mirror/blob/master/LICENSE`. The release badge points at `vis2k/Mirror/releases/latest`. The AppVeyor build badge targets a project named vis2k73562/hlapi-community-edition, and the repository itself carries an appveyor.yml alongside a `.releaserc.yml` and a setversion.ps1 PowerShell script. Meanwhile the repository you are reading is MirrorNetworking/Mirror, and the game gallery and forum links at the top point at the MirrorNetworking organization. So the file documents a project that changed hands, and the links are the fossil record. vis2k was the original author, and the project began as HLAPI Community Edition, which is what the AppVeyor project name still says. GitHub redirects the old paths, so nothing is broken, but the badges are a useful reminder of the project's age. This also explains the second legacy term you will meet in the topic list: hlapi, Unity's High Level API, the predecessor to UNET. Understanding the HLAPI to UNET to Mirror lineage explains a lot about the API shape, because Mirror deliberately kept the familiar surface so that developers could move across generations without relearning the concepts. For documentation, the README points at a GitBook at mirror-networking.gitbook.io, a Unity forum thread describing Mirror as HLAPI Community Edition, a Trello board for the roadmap, and a Discord invite. The project homepage is mirror-networking.com. The README also asks that the gallery of games built with it be linked from a section of the same name, which is the community's own catalogue of shipped titles. ## What the feature table marks stable Mirror presents its capabilities as a table with a status column, which is more honest than most engine feature lists because it tells you which parts have had years of production use and which are new. Marked stable and worth knowing by name: transports covering UDP, TCP, WebSockets, Steam, and Relay among others; interest management through spatial hashing and a distance checker to partition the world; SyncDirection giving you server or client authority per component with one click; latency simulation that adds lag, packet loss, and jitter locally; batching that reduces message overhead automatically; RPCs and SyncVars as built-in synchronized variables and remote procedure calls; allocation-free runtime behavior with no garbage collection except inside the transports; transform and physics synchronization; networked components on child objects; IL post processing, which the README describes as zero overhead RPCs and commands; and optional two-click hosting that builds and pushes directly from the Unity editor to the cloud. Two of those deserve unpacking because they are the ones developers actually argue about. Allocation-free is the one that changes how you write gameplay code. A runtime that does not allocate means no per-frame garbage, which on Unity means no GC spikes, which is what keeps frame times smooth in a busy scene. The exception the README names is the transports, which allocate internally. IL post processing is the one that is hard to find elsewhere. Instead of intercepting network calls at a higher level, Mirror rewrites the IL of your methods so the call site itself carries the network overhead, and the README's claim is that this adds nothing to the call. The same idea appears in the Telepathy serialization library, and it is the reason Mirror can claim batching and allocation-free behavior together rather than as separate optimizations. The snapshot interpolation feature is also marked stable, described as perfectly smooth movement for all platforms and genres. That is the system that smooths remote entity positions on the client, and it is the piece that separates a playable prototype from a game where other players teleport. ## Lag compensation, encryption, and cheat detection are still beta The bottom of the same table lists four features that are not yet in the same category. Lag compensation is marked beta and described as rolling back state to see what the player saw during input. This is the classic shooter technique: when a player fires, the server rewinds the world to where that player's client saw it, evaluates the shot, then restores the present. It is the difference between a hitscan feeling fair and feeling broken, and the beta label means you should test it against your own movement model rather than assume it handles your specific case. Encryption is also beta, described as secure communication with end-to-end encryption. The word end-to-end deserves attention in a networking library: it implies the transport encrypts rather than relying on TLS at the edge, which matters for anything competitive where packet contents should not be readable in transit. Cheat detection is beta as well, and the description names the specific threat it targets: Mirror Guard safely detects Melon Loader and more. Melon Loader is a well-known modding framework for Unity games, so detecting it is a narrow, concrete goal rather than a general anti-cheat. Plan your security posture around that scope. Unreliable messaging appears at the end of the feature table with no status value beside it, which tells you the list of capabilities continues past the rows shown. Read together, the stable and beta halves give a clear picture of where Mirror is strong. Networking correctness, synchronization, bandwidth, and smooth interpolation are mature. The adversarial half of multiplayer, which is where cheating, latency deception, and confidentiality live, is young. If you are shipping a competitive title, treat the beta features as something to evaluate rather than something to depend on. ## The repository is a Unity project, not a library package The tree explains something that trips up people cloning Mirror for the first time. There is an Assets directory, a Packages directory, and a ProjectSettings directory, which means this repository is a complete Unity project rather than a bare library folder. That arrangement is a deliberate consequence of how Unity packages work. Unity expects code to live inside a project, so the most reliable way to develop and test a networking library is against a real project with a real scene. The trade-off is that the useful code is buried inside a project you did not write, and the repository root is full of things that only make sense in that context. The surrounding tooling is a good map of the project's age and habits. appveyor.yml is the continuous integration config, which is old but still supported and still pointed at by the README badge. .codecov.yml is there for coverage reporting, .releaserc.yml indicates that releases are automated rather than uploaded by hand, and setversion.ps1 is a PowerShell script that stamps a version into the project. CONTRIBUTING.md and SECURITY.md exist at the root, and a FUNDING.yml alongside funding.json shows sponsorship is set up. remote_statistics.txt is an unusual file to find and appears to track usage telemetry of some kind. The .mcp.json file at the root is a more recent addition and points to the same direction the melonJS repository took: an explicit configuration for model context protocol tooling, which for a project of this age suggests maintainers are inviting agent-assisted contributions. For consumption, the README leads with the Unity Asset Store listing rather than a package manager. GitHub Packages, a UPM git URL, or vendoring the source into your own project are the alternatives, and the documentation site is where the current guidance lives rather than the README. ## Version numbers that encode a date The release tags do not look like software versions, and understanding why saves you from misreading them. The three most recent tags are v96.11.3 on 2026-09-17, v96.11.2 on 2026-08-22, and v96.11.1 on 2026-08-22. Two releases on the same day, then a patch two days later, and the major-looking component has nothing to do with the number of breaking changes. This is a date-derived scheme where the leading numbers track a release calendar rather than a semantic version contract. That has a concrete consequence for dependency management. Semver tells you whether an update is safe, but a date-stamped tag does not, so you cannot reason about risk from the version number alone. The practical approach for a Unity project is to pin an exact tag rather than a floating branch, read the release notes for the jump you are making, and expect to test. It also tells you something about the project's relationship to its users. Mirror has been in continuous release since 2014 and there are millions of players behind it, so the maintainers appear to be optimizing for shipping fixes continuously rather than for long quiet periods between major versions. For a studio with a dedicated networking engineer, that is a good trade. For a solo developer, it means your build is a moving target unless you pin it. The fork and issue numbers give a sense of the maintenance burden. With 6,337 stars, 871 forks, and 68 open issues, the ratio suggests most users are not filing tickets, and the fork count reflects how many people have carried a private branch rather than a large crowd of casual contributors. If you are evaluating Mirror against a commercial alternative, the two things worth checking in your own environment are the transport you need, since Steam and Relay sit alongside the plain UDP and TCP options, and the two-click hosting path, which is the feature that determines whether you need to operate your own relay infrastructure or hand that to a cloud provider. ## Conclusion Mirror is the networking layer to reach for when a Unity project needs real multiplayer and the budget stops short of a commercial netcode license. The reason is durability rather than feature count: the project has been shipping since 2014, it holds an MIT license rather than a seat license, and it is still cutting releases in the 20 hundreds version line with commits landing weeks ago. Two cautions before you adopt it. First, several systems in the feature table are marked beta, including lag compensation, end-to-end encryption, and cheat detection, so do not build your anti-cheat strategy around Mirror Guard alone. Second, the README's usage numbers are self-reported, and the links in its badges still point at the older vis2k organization, which tells you the project is healthy but that its documentation front page lags the code. If you want certainty about adoption, the Unity Asset Store listing and the SteamDB SDK page linked from the README are the two places to check with your own eyes. ## FAQ ### What is the Mirror networking library for Unity? An MIT licensed C# networking library for Unity games, originally based on Unity's UNET and in continuous use since 2014. It provides RPCs, SyncVars, transform and physics synchronization, snapshot interpolation, interest management, batching, and a choice of transports covering UDP, TCP, WebSockets, Steam, and Relay. The repository is MirrorNetworking/Mirror with its homepage at mirror-networking.com. ### Is Mirror free for commercial Unity games? Yes. Mirror is MIT licensed, with a LICENSE file at the repository root, so you can read, modify, and ship it in a commercial product without a seat fee or revenue reporting. The project does accept sponsorship through FUNDING.yml and funding.json, but the license does not make support a precondition of use. ### Which Mirror features are still in beta? Lag compensation, end-to-end encryption, and cheat detection. Cheat detection is scoped narrowly: the README describes Mirror Guard as detecting Melon Loader and similar modding frameworks rather than providing general anti-cheat. Snapshot interpolation, transforms, RPCs, batching, and interest management are all marked stable, so the mature half of the library is synchronization and bandwidth rather than the adversarial half of multiplayer. ### How do I install Mirror in a Unity project? The README leads with the Unity Asset Store listing. GitHub Packages, a Unity Package Manager git URL, or vendoring the source into your own project are the other routes. Note that the repository is a full Unity project with Assets, Packages, and ProjectSettings directories rather than a bare library folder, so cloning it gives you the development project, not a clean drop-in, and the current guidance lives on the GitBook documentation site. ### How many games use Mirror? The README states that Mirror is used by over 200 million players and powers major releases such as Population: ONE plus over 1000 games on Steam. Those are figures the project reports about itself. To check independently, the README links the SteamDB SDK page, which lists the Steam titles that declare Mirror as a technology, and the Unity Asset Store listing shows the download and rating counts on its own page. ## Sources - [License: MIT](https://github.com/MirrorNetworking/Mirror/blob/master/LICENSE) - [MirrorNetworking/Mirror on GitHub](https://github.com/MirrorNetworking/Mirror) - [Project website](https://mirror-networking.com) - [README](https://github.com/MirrorNetworking/Mirror/blob/master/README.md) - [Releases](https://github.com/MirrorNetworking/Mirror/releases) --- Hysen Labs editorial analysis, written from the project's own repository and release notes. Cite the canonical page: https://hysenlabs.com/projects/mirrornetworking-mirror