Markdown Companion
Read what your AI writes.
Your projects are full of Markdown written by coding assistants — plans, READMEs, agent notes. Chrome shows them as a wall of raw text. Markdown Companion turns them into a clean, readable page and shows you exactly what changed on every save.
- 100% local
- No account
- No telemetry
- Free
Works with .md, .markdown, .mdown, .mkd and .mdx files on your disk.
Why now
Markdown became the language between you and your AI tools.
Agents read your docs for context, and write their plans, reports and memory files back as .md. Markdown Companion is the human side of that bridge — no AI runs inside it; it is the reading and review surface for the AI already in your workflow.
They write more than you do
Every coding session leaves behind READMEs, plans, changelogs and notes. Reading them in raw form is where understanding quietly dies.
Reading is reviewing
A doc your agent wrote is a claim about your project. Rendered headings, task lists and diffs turn skimming into an actual review.
Private by architecture
The documents describing your codebase never leave your machine — there is no server to send them to.
The feature nobody else has
See exactly what changed, on every save.
Auto-reload watches the file on disk. When your editor — or your AI assistant — saves it, Markdown Companion shows a diff of precisely what changed before you accept the reload.
- Watch an agent's edits land in a plan, line by line
- Catch the paragraph that quietly disappeared
- Accept the reload when you've seen it — or let it apply automatically
Illustration — the real diff view renders GitHub-style, inline in the reader.
Everything for reading
A complete markdown reader, not a preview.
Built for Manifest V3 from scratch, and verified by an automated conformance suite on every build.
Complete Markdown Guide coverage
Tables, task lists, footnotes, definition lists, heading IDs, highlight, sub/superscript, emoji shortcodes — all on by default, no settings to flip.
Diagrams and math, inline
Mermaid diagrams and KaTeX math render right in the page — architecture sketches and formulas your tools generate, readable at last.
Navigate the whole folder
A sidebar lists every markdown file next to the one you're reading, plus a parent-folder link — a docs directory becomes a browsable space.
Outline with scroll-spy
A document outline tracks where you are and jumps anywhere on click. Keyboard shortcuts cover theme, panels, reading mode and width.
Your reading, your rules
Light, dark and sepia themes, high-contrast mode, adjustable font, width and line height, and a print stylesheet.
Verbatim and sanitised
No typographic rewriting — a --flag in a runbook stays a --flag. Embedded HTML renders only after sanitisation.
Two minutes, once
Setup that doesn't fail.
Chrome hides one toggle that every local-file extension needs. Markdown Companion walks you through it on first install instead of leaving you to find out the hard way.
- Add to ChromeInstall from the Chrome Web Store — no account, nothing to configure.
- Allow file accessChrome requires "Allow access to file URLs" for local files. The extension guides you to the exact switch.
- Open any .md fileDrag it into a tab or press Ctrl+O — it renders instantly, with the whole folder one click away.
No server. No account. No telemetry.
Markdown Companion runs entirely inside your browser. File contents never leave your machine — read the two-minute privacy policy, there's honestly not much to it.
Frequently asked
Why do I need to enable "Allow access to file URLs"?
Chrome doesn't let extensions read local files by default. Markdown Companion walks you through enabling this once, in chrome://extensions. The extension can't and doesn't flip it for you.
Which file types does it support?
.md, .markdown, .mdown, .mkd, and .mdx.
Does it render Mermaid diagrams and math?
Yes — Mermaid diagrams and KaTeX math render inline, bundled with the extension. No network requests are made to do it.
Does it work offline?
Yes. Everything runs locally in your browser — no connection required.
Is my data sent anywhere?
No. File contents never leave your machine. There's no server, no account, and no telemetry.
Is it free?
Yes — reading, folder navigation, themes, diagrams and the diff view are free.
Your docs deserve better than raw text.
Install once, and every markdown file on your machine becomes a page worth reading.