MDHero

MDHero opens local Markdown documents, pasted Markdown and explicitly fetched public URLs in a readable interface. It suits writers and developers reading READMEs, notes, AI chat exports and project plans who want occasional in-place editing without a full IDE. It provides light/dark themes, reader typography controls, syntax highlighting, KaTeX equations, Mermaid diagrams, a heading sidebar, search and keyboard/Vim-style navigation.

Files, edits and exports

Open several documents in tabs, reorder them, pin folders or use recent files. Local file watching reflects edits made in another editor. Cmd+E switches a local file to edit mode and Cmd+S writes it back to disk; unsaved-state indicators and close confirmation help avoid losing edits. Print/PDF export uses the native print dialog. Rich-text or Markdown copying lets you move content to another application, where formatting may differ. It is a lightweight editor/viewer, not a guarantee of exact formatting compatibility with every Markdown extension.

Mac installation and hardware

The exact 0.2.10 Apple Silicon DMG is 11,508,920 bytes in the official GitHub asset metadata. The tagged README and release list Apple Silicon Mac installation; use other OS/CPU artifacts only where explicitly offered. Download the DMG, move MDHero to Applications and open it once. Release 0.2.10 is the first officially notarized/stapled Mac DMG, unlike earlier signed-only builds. Follow ordinary macOS security prompts rather than disabling Gatekeeper globally.

The checked tagged README/config do not state a numeric effective minimum macOS or RAM requirement. Those remain explicit documentation gaps; Tauri's use alone does not prove a complete OS minimum. Large files, images, math and diagram rendering need more resources than the installer size. Node22, Rust and pnpm10 in development instructions are source-build prerequisites, not needed to read files with the installed app. No account or external AI model is needed to render pasted AI output.

Quick Look and permissions

0.2.10 adds Finder Quick Look: select a .md file and press Space. Launch the app once to register its extension; if raw text still appears, enable MDHero under System Settings → General → Login Items & Extensions → Quick Look. File open/save, pinned folders, recent paths and plan-directory discovery access documents on your Mac; grant only intended filesystem access. It can discover ~/.claude/plans, so avoid exposing a shared machine's private project plans through previews or screenshots.

License, privacy and network

MDHero is MIT-licensed by Vaibhav Kakde and is free to use without an account. The tagged README states no analytics/tracking and local rendering, with networking for release checks (once per24hours) and URLs you explicitly request. Treat this as the publisher's documented behavior, not independent verification of every dependency. Remote images embedded in Markdown and external links are also potential network/privacy considerations; inspect untrusted content and the actual rendering behavior before using sensitive documents. The tagged CSP permits HTTPS images, so a local document must not be assumed to block every remote asset by default.

Fetching a URL sends a request to that service; public URL support is not an authentication client for every private repository. Clipboard contents, file paths, local previews and printed/exported PDFs can remain accessible to other apps/users according to macOS permissions. Review the rendered document and exported file before sharing. The 0.2.10 file-link allow-list limits OS opening to specified document/media types; it is not a claim that arbitrary untrusted content is safe.

Reliability and risks

Keep backups before editing originals, particularly while another editor watches the same file. Verify diagrams/math and external assets after export. Updated dependencies and file-link restrictions address security concerns, but do not turn rendering into proof that a linked file is trustworthy. Only0.2.10 is present as a distinct version in this fixed catalog; no older catalog records are invented.

Sources: Official project, Tagged README/privacy, Exact release, Security configuration, MIT license.