Markdown Validator Box

Tired of guessing whether your Markdown will render the way you expect? MD Box is a focused, offline Markdown editor that validates your syntax as you type and shows a live rendered preview right next to your source — no surprises when you publish, commit, or export.

Start typing and watch the preview update instantly with rendered headings, bold and italic text, lists, tables, and syntax-highlighted code blocks. A glowing status badge tells you at a glance whether your document is valid, has warnings, or contains errors — tap it to jump straight to the problem line.

HOW IT WORKS

Open MD Box and start writing. The app parses your Markdown continuously and gives you feedback without ever leaving the keyboard:

• Type or paste Markdown into the monospace source editor
• Watch the live HTML preview render side-by-side or stacked, depending on screen size
• Check the validity badge for an instant read on syntax health
• Tap any flagged error or warning to jump the cursor straight to that line
• Export your finished document as clean, standalone HTML whenever you're ready

Everything happens locally on your device in real time — no network calls, no waiting.

KEY FEATURES

• Live split-screen or stacked Markdown preview that updates as you type
• Real-time syntax validation for headings, lists, links, tables, and emphasis
• Tap-to-jump error and warning navigation straight to the offending line
• Detailed validation report covering unclosed tags, broken tables, and mismatched headings
• One-tap export to standalone, styled HTML files
• Copy compiled HTML directly to your clipboard for pasting anywhere
• Full undo and redo history while you edit
• Optional syntax highlighting for fenced code blocks in the preview
• Character, word, and line counters that update live as you write
• Auto-save drafts locally so you never lose your work
• Adjustable workspace layout — side-by-side on wide screens, stacked on phones
• Dark Amber, true AMOLED black, or system-matched theme options
• Built-in Markdown cheat sheet for quick syntax reference
• Guided setup quiz to configure your ideal writing environment on first launch

PERFECT FOR

• Developers writing README files, changelogs, and technical documentation
• Bloggers and writers who draft in Markdown before publishing
• Students and note-takers who want clean, structured formatting
• Anyone preparing content for static site generators or GitHub
• Writing offline on flights, commutes, or anywhere without signal
• Catching formatting mistakes before they reach a live site or repository

WHY MD BOX

Most Markdown tools either skip validation entirely or bury syntax checking behind a paid plan. MD Box treats validation as a first-class feature: the moment something breaks — an unclosed code fence, a malformed table, a mismatched heading level — you'll know immediately, with a direct line reference.

A short setup quiz lets you pick your layout, highlighting, autosave, and theme tone before you write a word. Every choice can be revisited anytime from settings, including retaking the quiz or switching between Dark Amber and true AMOLED black.

When ready, tap Export to copy fully-styled HTML to your clipboard or save it as a standalone .html file — complete with styled headings, code blocks, tables, and blockquotes.

PRIVACY & TRUST

MD Box works entirely offline and never transmits your Markdown, drafts, or exported HTML to any server. Parsing and rendering happen locally via the Commonmark engine. Drafts live in a local database you can clear anytime from settings. No accounts, no logins, no telemetry.

Download MD Box today and write Markdown with confidence, knowing exactly what will render before you hit publish.

Recent changes:
New version!