Show HN: Marky – A lightweight Markdown viewer for agentic coding | AI Paper Digest

TL;DR Highlight

This macOS desktop app allows you to open Markdown files generated in real-time by AI agents like Claude directly in the terminal and view them with live rendering. It simplifies the document review process in AI-powered development workflows.

Who Should Read

macOS developers who want to quickly check planning documents, READMEs, notes, and other files generated while coding with AI agents (Claude, Cursor, etc.). Especially those who want to conveniently manage a large number of Markdown files output by an agent.

Core Mechanics

Marky is a macOS-exclusive desktop app that instantly renders Markdown files or folders with a single command in the terminal: `marky FILENAME` or `marky FOLDER`.
It supports live reload, so the viewer screen automatically updates when Claude or an editor modifies the file without requiring a separate refresh. You can see the content in real-time as the AI writes the document.
If you register a folder as a workspace, a file list appears in the sidebar like Obsidian, and it is automatically restored even when the app is restarted.
You can fuzzy search all files in registered folders with Cmd+K command palette, and it internally uses the nucleo library.
Code blocks are rendered with Shiki (the same syntax highlighting engine as VS Code), equations with KaTeX, and diagrams with Mermaid as SVG rendering. It supports the entire GFM (GitHub Flavored Markdown).
HTML rendering is sanitized with DOMPurify, so you can safely open untrusted Markdown files.
The tech stack is Tauri v2 (Rust-based desktop app framework) + React + markdown-it, and it can be installed with Homebrew or built directly from source.

Evidence

There was feedback that the term 'native' could be misleading. While Tauri uses the system WebView, it's an exaggeration to call it 'JavaScript native' since it's ultimately based on WebView.
Several people mentioned having created similar tools themselves. vantageapp.dev, sdocs.dev, seams, hyprmark, mdreader, and other similar projects were shared in the comments, demonstrating that the boom in AI agent development has led to a simultaneous increase in people trying to solve this problem.
The question 'What's the difference between this and Obsidian?' was raised. Obsidian also supports folder views and Markdown rendering, and the distinction was unclear. There were no clear rebuttals, and the comment did not lead to further discussion.
There was also the opinion 'VS Code + Markdown preview is almost the same functionality.' However, this comment also included a specific need: integration with git and highlighting changes made by the agent.
A UX inconvenience was reported: the text size cannot be adjusted. Along with feedback that the sidebar column width cannot be adjusted, there were real-user opinions that the default size is small and strains the eyes.

How to Apply

Have an AI agent like Claude or Cursor write a planning document or spec file in Markdown, then open the corresponding folder in a separate terminal with the command `marky ./plans/` to view the content live as the agent updates the files.
In projects where an agent generates a large number of Markdown files, open the project root with `marky .` and quickly find the desired file with Cmd+K fuzzy search. It is possible to quickly navigate even if more than 75 files are generated.
Since it supports Mermaid diagram and KaTeX equation rendering, you can prompt the AI to write system architecture or flows in Mermaid code blocks and instantly visualize them in Marky.
Because DOMPurify sanitization is applied, you can safely render and view Markdown files received from untrusted sources without the risk of XSS when checking documents received from outside.

Code Example

snippet

# Installation (Homebrew)
brew install marky

# Open a single file
marky README.md

# Open the entire folder as a workspace
marky ./docs/

# Open the current directory
marky .

Terminology

TauriAn alternative to Electron, a desktop app framework built with Rust. It uses the system WebView, resulting in a much smaller app size and lower memory usage.

GFMAbbreviation for GitHub Flavored Markdown. A specification that adds extensions used by GitHub, such as tables, checkboxes, and strikethroughs, to standard Markdown.

ShikiThe same syntax highlighting engine actually used by VS Code. It colors code blocks accurately and beautifully.

KaTeXA library for quickly rendering LaTeX mathematical formulas on the web. It displays formulas like $f(x) = x^2$ in a readable format.

MermaidA tool that allows you to draw flowcharts, sequence diagrams, etc. with code. When mermaid is specified in a fenced code block, it is automatically converted to an SVG image.

DOMPurifyA sanitize library that removes dangerous tags or attributes that could be used in XSS (cross-site scripting) attacks from HTML strings.

Show HN: Marky – A lightweight Markdown viewer for agentic coding