How to read Claude and ChatGPT markdown beautifully on a Mac

Claude, ChatGPT and every coding agent write in markdown. Saved to a file, that turns into a wall of pound signs and asterisks. It doesn't have to.

Why AI answers come as markdown

Markdown is plain text with a few marks for structure: # for headings, ** for bold, dashes for lists, backticks for code. Language models write it naturally, and chat apps render it for you in the window. The moment you download a response, export a chat, or open a README.md or PLAN.md an agent wrote, you are back to the raw text.

Three ways to read it

1. Paste it back into a chat window

Works for a paragraph. Painful for a long report, and it doesn't help with files already on your disk.

2. Open it in an editor

Code editors like VS Code have a markdown preview pane. It is accurate, but it looks like a developer tool, because it is one.

3. Open it in a reader

A markdown reader renders the file as a finished page the moment you open it. That is what Lumd is for: double-click any .md file and it opens with real typography, proper spacing, syntax-highlighted code, Mermaid diagrams, math, tables and task lists.

Make it beautiful, not just readable

Long AI output is easier to read when it is set like a book rather than a terminal. Lumd ships 14 handcrafted themes (6 of them free), each with its own typefaces and palette. Read a research summary in warm parchment, a project brief in a crisp sans, a late-night plan in a dark theme. The outline sidebar lets you jump between sections of a long answer.

Keep it private

AI output often contains work in progress: plans, code, drafts with names in them. Lumd renders everything on your Mac. No upload, no account, and it works offline.

A simple workflow

  1. Ask your AI tool to save its answer as a .md file, or download it from the chat.
  2. Make Lumd your default app for .md files once (Finder → Get Info → Open with → Lumd → Change All).
  3. From then on, double-click to read. Press Space in Finder for a Quick Look preview in the same style.
  4. Need to share it with someone who doesn't use markdown? Export a PDF.