Read the source.
A calm, customizable Markdown reader for researchers and writers who need a quiet space to explore their work.
AI deep-research tools produce long Markdown documents. Writers collect notes, excerpts, references, and exported summaries. Traditional editors display Markdown well, but they always feel like editors first: panes, terminals, and the weight of features you don't need when you simply want to read.
Codex focuses on clarity and comfort. Open a single file or an entire folder of Markdown documents. Navigate them like a library. Switch themes. Read without the noise of an editor surrounding your work.
Codex uses a cyberpunk-inspired color palette that's easy on the eyes during long reading sessions.
Open individual Markdown files or entire directories as projects.
Two-pane layout with collapsible file tree for effortless browsing.
Built-in light and dark themes, plus support for custom JSON theme files.
Syntax highlighting, tables, task lists, and all GitHub-flavored Markdown.
Lightweight, native desktop app. No cloud, no tracking, no internet required.
Navigate, search, and switch themes with keyboard shortcuts.
Download the appropriate installer for your platform and run it. Codex is portable and can be run without installation on both Windows and Linux.
Codex themes are simple JSON files. Place them in
~/.codex/themes/ to load them in the app.
{
"name": "My Theme",
"version": "1.0.0",
"isDark": true,
"colors": {
"primary": "#6C3FDB",
"accent": "#00D9FF",
"background": "#0A0A0F",
...
}
}
Ctrl/Cmd + O — Open fileCtrl/Cmd + Shift + O — Open folderCtrl/Cmd + R — ReloadCtrl/Cmd + T — Toggle themeCodex is a personal, fully offline Markdown reader built with care for writers and researchers who want a quieter space to explore their work. If Codex has helped you, consider supporting its development.