Imark Guides

Eight guides, sorted by why you are here: a file that opened as source code, a document somebody wants your notes on, or a plan your coding agent is waiting for you to approve. Start with the group that matches.

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A .md file opened as source code

Four ways out, from the smallest change to the biggest. If you want the document readable in the next minute, start with how to open a .md file on a Mac. If the space bar in Finder is all you are missing, Markdown in Quick Look on a Mac is the lighter fix. If your documents carry diagrams or equations, settle that first with a Markdown viewer with Mermaid and KaTeX. And if you are still deciding what to install, the best Markdown viewer for Mac, nine apps compared has what each one charged in 2026.

  1. Open .md files on Mac

    How to Open a Markdown (.md) File on Mac: 4 Ways

    Four ways to open a Markdown file on a Mac, compared: TextEdit, an editor preview, Quick Look in Finder, and a free viewer. Plus how to set the default app.

    Read the guide

  2. Markdown Quick Look for Mac

    Quick Look Markdown on Mac: Free Space Bar Preview

    Preview Markdown in Finder with the space bar. A free, open source Quick Look extension that renders headings, code, tables, Mermaid diagrams and maths offline.

    Read the guide

  3. Technical Markdown

    Free Markdown Viewer with Mermaid and KaTeX for Mac

    Read Markdown with Mermaid diagrams, KaTeX maths, highlighted code, tables and local images. Free, open source, and rendered entirely on your Mac, offline.

    Read the guide

  4. Choose a Markdown app

    Best Markdown Viewer for Mac: 9 Compared (2026)

    Nine Mac Markdown apps compared in 2026: Imark, MacMD Viewer, Marked, QLMarkdown, Typora, Obsidian, MacDown and iA Writer, with prices, Quick Look and Mermaid.

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Someone is waiting on your notes

A review that lives in email or Slack is a review the document loses. Imark writes each note into the .md file itself, as an HTML comment no other viewer shows, so the notes travel with the file through Git and arrive with it. How to annotate Markdown files covers the whole round trip. When what you found is one wrong word rather than a note, editing Markdown in Imark saves you opening another app.

  1. Markdown review comments

    Annotate Markdown for Review: Notes Inside the File

    Annotate a Markdown file by commenting on exact phrases. The notes save inside the .md, travel through Git and email, and stay invisible in every other viewer.

    Read the guide

  2. Editing in Imark

    Edit a Line Without Leaving Imark

    Switch from the rendered document to its text, save safely, handle a change made elsewhere, and move a larger job to your usual editor.

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A coding agent wrote a plan

Claude Code and Codex write the plan first and then ask for a yes. That yes is the entire review: there is no way to say that step three is wrong. How to review an AI agent's plan is the reading half, and the Imark skill for Claude Code and Codex is the wiring that puts the plan in front of you and waits.

  1. Reviewing an agent's plan

    How to Review a Claude Code Plan Before Implementing

    Plan mode lets you accept a plan or send it back. It does not let you say that step 3 is wrong. What to check in an agent's plan, and how to comment on one.

    Read the guide

  2. Claude Code and Codex plugin

    Markdown Review Plugin for Claude Code and Codex

    Install the free plugin that opens an agent's Markdown on your Mac and waits: two commands, an optional plan mode hook, and what each one hands back.

    Read the guide