U-18chan is an English furry-themed bulletin board which was established after Aurorachan's /fur/ board merged with an IB4F board in 2009, then it went independent on December 2, 2010. According to the staff, the website is mostly focused on furry-themed pornography.

Back in 2009,¹⁾ Aurorachan had a /fur/ board that became known for raiding 4chan's “Random” (/b/) board to advertise themselves and troll. After a while, it became evident that the one-board approach was limiting, so “Serpentor” led the initiative. On June 26, 2009, “Filthy” (!zIArsem5L.) and “Jay” (AlienSloth Man) would set up FilthySlothChan at IB4F,²⁾ which would later become U-18chan on October 22, 2009.³⁾

At the time, the joke was that their community 'evaded raids' like a U-18 submarine.⁴⁾ The merge was then finalized by November 29, 2009,⁵⁾ then “Serpentor” apparently vanished from the staff shortly after.⁶⁾ During this, Aurorachan had actually kept its /fur/ board, since websites are allowed to have their own furry board, but eventually decided to remove the board in March 2010.

The staff had purchased three domains,⁷⁾ then IB4F's death⁸⁾ forced U-18chan to settle at “u18chan.com” with a fresh Kusaba X installation on December 2, 2010.⁹⁾ U-18chan temporarily borrowed Krautchan's mascot, Heinrich, before replacing him with Valkyria on July 13, 2011.¹⁰⁾ They eventually realized Kusaba X was bad, so U-18chan requested the IB4F fork of Kusaba X from “Infinitus” on July 28, 2011.¹¹⁾¹²⁾

In 2016, a power surge killed their hard drive,¹³⁾¹⁴⁾ so they salvaged what they had, changed datacenters, and rebuilt the server by July 24, 2016.¹⁵⁾¹⁶⁾ The news post¹⁷⁾ would show an incorrect start date.¹⁸⁾ Considering the political climate, the U-18chan staff decided to issue a statement on the 'Pawstika' logo and its early history with the 'AuroraFurries' on April 18, 2017.¹⁹⁾

During the 2023 server failure, U-18chan would start advertising the website's official Discord server because they managed to forget who had access to the official FurAffinity and Twitter accounts.²⁰⁾ During this time, rebranding efforts to move away from the 'Pawstika' had began, but the changes to the logo, favicon, and front page mascot wouldn't go into effect until April 2025 as they were busy with technical problems.

^{Note: This list was retrieved on 2021-11-14. It may have changed since then.}

• The U-18chan mascot, Valkyria, is a female sergal that had an SS uniform. She was designed by “YuuriArtz” (Yuuri)²¹⁾ and named in a community vote that concluded on August 28, 2011.²²⁾
• U-18chan used to have a “Scalies” (/scale/) board, but it was closed in 2017 and eventually deleted.

• Fchan and Lulz.net - Similar furry-themed websites from the 2000s.

• U-18chan - The front page of U-18chan.
  • @u18chan on Twitter - The official U-18chan account, though it hasn't updated since 2019.
• U-18chan on WikiFur