Codex Skin Codex themes is a theme gallery and customization workflow for the Codex desktop app in ChatGPT. It helps developers browse, install, apply, and switch curated visual themes on macOS and Windows through a free Codex Skin Plugin. Users can also restore the official Codex appearance when needed. The gallery provides dedicated theme details, stable six-digit theme IDs, Free and Pro theme collections, and compatibility checks before applying a theme. Users install the open-source plugin through Codex Marketplace commands, authorize their device, copy a theme ID, and apply or switch themes from inside Codex. Themes use signed, data-only assets rather than arbitrary theme code, while failed applications keep the previous appearance or roll back safely. Offline restore is available without website login, network access, active Pro access, or the plugin cache. Codex Skin gives developers a reversible way to personalize long coding sessions without replacing the official application or modifying signed system files. A free library is available, while Pro adds the full theme collection, new compatible releases, and annual switching access.