Pretendo is described as 'Open source Nintendo Network replacement that aims to build custom servers for the Wii U and 3DS family of consoles. Our goal is to preserve the online functionality of these consoles, to allow players to continue to play their favorite Wii U and 3DS games to' and is an website. There are three alternatives to Pretendo, not only websites but also apps for a variety of platforms, including Mac, Windows, Linux and Self-Hosted apps. The best Pretendo alternative is Brewtendo, which is both free and Open Source. Other great sites and apps similar to Pretendo are XLink Kai and Wiimmfi.
Brewtendo is a Nintendo Network revival for the 3DS, it's not really trying to be a potential Pretendo rival, however. Instead it revives the things that they wouldn't add such as the eShop, Badge Arcade, Theme Shop, Spotpass, and Nintendo Video.
XLink Kai is a global gaming network - bringing together XBox 360, XBox, Playstation 3, Playstation 2, Gamecube and PSP users, in one integrated community. It is software running on your PC or Macintosh that allows you to play system-link enabled games online for free.
A tool which brings back Nintendo Wi-Fi Connection, allowing to play online games on your Wii & all DS family (including 3DS).
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