Markdown preview on Mac for local document review
Markdown drafts are easy to copy and easy to misread. Preview the rendered structure locally before a README, release note, support reply, or internal spec leaves your Mac.
The short answer: use a local Markdown preview for the first review pass when the draft includes private notes, unreleased copy, customer context, internal links, or code snippets. Check headings, lists, tables, task lists, blockquotes, and code fences locally. Then use the destination docs platform when exact rendering or deployment behavior matters.
TeenyTool includes Markdown Preview in its Mac menu bar toolbox. I build TeenyTool, so the bias is clear. The honest boundary is also clear: it is good for a fast local structure check. It is not a full documentation site, GitHub renderer clone, linter, grammar editor, or source-control review tool.
This guide is the TeenyTool spoke for the TeenyApps hub, Mac document review checklist for Markdown and monitors. The monitor side is covered by TeenyDisplay's guide to Mac external monitor setup for document review.
Markdown preview decision table
| Review job | Use local preview when | Use the final renderer when |
|---|---|---|
| README draft | You need to read headings, lists, tables, links, and code before the draft goes public. | Repository-specific badges, anchors, alerts, or extensions affect the final page. |
| Support note | The note includes customer context, internal links, log excerpts, or private wording. | The support system changes Markdown rules or strips some formatting. |
| Release note | You need a local pass on headings, bullets, task items, and pasted snippets. | The changelog site adds callouts, automatic links, or custom components. |
| Internal spec | The draft includes code blocks, tables, and decisions that should stay on the Mac. | The final review depends on comments, version history, permissions, or approvals. |
01Start with the source and audience
Do not preview Markdown in isolation. First decide what the text is and who needs it. A README needs headings that help a new user scan. A release note needs bullets that do not hide breaking changes. A support reply needs links and code blocks that the recipient can follow without guessing.
That source label changes the review. If the draft came from an internal ticket, a customer email, a log, a private repo, or a launch note, keep the first pass local. If the text is public documentation, a web preview may be fine, but a local preview is still faster for small edits.
The broader Mac document review checklist uses the same rule: separate source review, rendered preview, display readability, and handoff evidence.
02Preview structure before polishing words
The useful first pass is structural. Does the page have one clear H1? Do H2s split the reader's decisions? Are bullets nested in a way that still reads? Are task list items checked only when the work is actually done?
TeenyTool's Markdown Preview source parses H1, H2, H3, paragraph text, bullet lists, ordered lists, task list items, blockquotes, horizontal rules, fenced code blocks, and simple pipe tables. It renders inline Markdown through Apple's AttributedString Markdown parsing with inline syntax enabled.
That combination is enough for the manual review moment before a short document leaves your Mac. It is not a promise that every Markdown extension will match GitHub, a docs platform, a wiki, or a static-site generator.
03Check tables and code blocks separately
Tables and code blocks are where Markdown drafts often break. A table can look aligned in raw text and still render with a missing cell. A code fence can lose indentation or hide a copied character. A support snippet can include a token that should have been removed before sharing.
Use local preview to make those failures visible before the draft reaches the target app. For tables, check the header row, separator row, row count, and the longest cell. For code fences, check indentation, line wrapping, language labels, and whether the code should be shortened or redacted.
If the Markdown came from copied text, run the cleanup pass first. The related guide to clean copied text on Mac with local utilities covers trimming, case fixes, find and replace, sorting, line numbering, and word counts before the preview step.
04Keep private drafts local until they belong elsewhere
A Markdown preview task can look harmless because it is "only text." The text may still contain a customer name, internal URL, unreleased pricing line, private API route, launch note, product decision, or copied log excerpt.
TeenyTool's homepage says most tool inputs stay on the device and identifies the network-specific exceptions, such as IP Address and DNS Lookup. Markdown Preview is a local text tool, so it fits the private first-pass review. Use the final docs system when the document belongs there, not because a web preview happened to be open.
Write a short handoff note after the local pass: what changed, what still needs platform-specific review, and which source or issue owns the final wording. That note stops a local preview from pretending to be final approval.
05Know the renderer boundary
Markdown is a family of formats, not one universal rendering contract. CommonMark is the useful baseline for core syntax. Many real systems add their own pieces: issue links, heading anchors, alerts, diagrams, footnotes, task-list styling, front matter, syntax highlighting, and custom components.
Use local preview to catch obvious structure problems early. Use the final renderer for anything tied to platform behavior. If the destination page uses a docs theme, product website, GitHub README, help center, or release-note CMS, check that destination before publishing.
The local preview should reduce risk before handoff. It should not replace the system that owns the public page.
06Pair the preview with a readable display
Rendered Markdown is easier to judge when the review window is readable. If the font feels too small, the contrast feels off, or the external monitor is using the wrong resolution, you start editing around a display problem instead of a document problem.
For monitor state, use the TeenyDisplay guide to set up an external monitor for document review on Mac. Put the preview, source, and notes where you can compare them without dragging windows across displays during the review.
This matters most for Markdown tables, long bullets, and code blocks. A readable preview makes weak structure easier to see.
Ten-minute local Markdown review
- Label the draft: README, support note, release note, internal spec, or handoff note.
- Remove private values that do not belong in the final document.
- Paste the Markdown into a local preview.
- Check H1, H2, and H3 order before editing sentences.
- Review bullets, ordered lists, task list items, and blockquotes.
- Inspect tables for missing cells and code blocks for bad wrapping.
- Open the destination renderer when exact platform output matters.
- Write a short handoff note with remaining checks and source links.
Sources checked
- TeenyTool claims were checked against the TeenyTool homepage and local Swift source for
Tool.swiftandMarkdownPreviewView.swift. - CommonMark Spec for the core Markdown baseline.
- Apple Developer Documentation: AttributedString.
- Apple Developer Documentation: MarkdownParsingOptions.
FAQ
Can I preview Markdown on Mac without uploading it?
Yes. A local Markdown preview lets you paste a README draft, support note, release note, or docs snippet into a Mac app and inspect the rendered structure without sending the text to a browser tool.
Does a local Markdown preview replace checking the final docs platform?
No. Use local preview for the private first pass. Check the final docs platform when exact renderer behavior, extensions, anchors, callouts, or deployment styling matter.
What should I check in a Markdown preview?
Check heading order, links, lists, tables, code fences, task lists, blockquotes, horizontal rules, private snippets, and whether the rendered page is still readable on the display where you review it.