Unity3D Networking

Unity Networking extension DLL – open source component of the Unity Multiplayer Networking system
https://bitbucket.org/Unity-Technologies/networking/src/2bdd9961092c?at=5.4
https://blogs.unity3d.com/2015/11/19/high-level-multiplayer-networking-layer-has-been-open-sourced

Unity Networking – Unity Tutorial: Authoritative Networking [No plugins] [C# & JS]
http://createathingunity.blogspot.co.uk
https://www.youtube.com/watch?v=QfzrpxO89tU

Photon Unity Networking Free
https://www.assetstore.unity3d.com/#!/content/1786?aid=1101lGsK

Photon PUN+
https://www.assetstore.unity3d.com/#!/content/12080?aid=1101lGsK

TNet: Tasharen Networking
https://www.assetstore.unity3d.com/#!/content/56798?aid=1101lGsK
http://www.tasharen.com/?page_id=4518

Good ol’ Sockets – brings the power of .NET sockets to mobile developers without the need for Pro license
https://www.assetstore.unity3d.com/#!/content/13166?aid=1101lGsK

Photon Bolt – networking middleware
https://www.assetstore.unity3d.com/#!/content/41330?aid=1101lGsK
http://www.boltengine.com
https://www.assetstore.unity3d.com/en/#!/content/18358
http://forum.unity3d.com/threads/released-bolt-the-new-generation-of-networking-solution-for-unity.248912

UnityPark Suite Indie Licence / per game – uLink, uLobby, uGameDB and uZone
http://developer.muchdifferent.com/unitypark/Downloads

UnitZ – Multiplayer FPS sandbox starter kit
https://www.assetstore.unity3d.com/#!/content/26912?aid=1101lGsK

SmartFoxServer – massive multiplayer server for MMO
https://www.assetstore.unity3d.com/#!/content/17261?aid=1101lGsK
http://www.smartfoxserver.com

Exit Games – Game Network Engines, MMO Server
http://www.exitgames.com

Irc Chat
http://forum.unity3d.com/threads/68070


Collection of multiplayer samples
http://forum.unity3d.com/threads/collection-of-multiplayer-samples.355642

UNet Sample Projects – 2D shooter, invaders, tanks, Network Starter, move, transport layer demo
http://forum.unity3d.com/threads/unet-sample-projects.331978

UNet Tutorial
https://www.youtube.com/user/GamerToGameDeveloper/videos?shelf_id=0&view=0&sort=dd
http://www.gamertogamedeveloper.com/download

UNET Unity 5 Networking Tutorial – Introducing the HLAPI
http://www.gamasutra.com/blogs/ChristianArellano/20150922/254218/UNET_Unity_5_Networking_Tutorial_Part_1_of_3__Introducing_the_HLAPI.php