In the context of Minecraft and Eaglercraft, "hacked clients" are modified versions of the game client that include illicit features such as "Kill Aura" (auto-attacking), "X-Ray" (seeing through blocks), and flight capabilities. These clients often bypass server-side anti-cheat plugins.
While links frequently change due to takedowns or domain migrations, the following names are frequently searched within the community: Eaglercraft Hacked Client Links
Most clients focus on bypassing the limitations of browser-based play or gaining an advantage on multiplayer servers: In the context of Minecraft and Eaglercraft, "hacked
Once the game loads, the cheat menu is typically opened using the Right Shift key or the Insert key. A Fair Warning: The Risks of Cheating "X-Ray" (seeing through blocks)