Markdown Browser Tools: read Markdown where you find it

Markdown Browser Tools started with a daily annoyance: reviewing AI-generated .md files. Agents write Markdown all day — plans, reports, documentation — and those files deserve to open like documents, not like source code.

Why the browser, and not another editor plugin?

The standard developer answer to Markdown is a preview pane in the code editor. It works — but look at what it quietly costs you.

Your reading tools live in the browser, not in the editor. Translation extensions that lay a second language under every paragraph. Highlighters and annotation tools that let you mark up what matters. Dictionary look-ups, read-aloud, clip-to-notes. Over the years you've assembled a reading toolkit in the browser — and none of it can reach inside an editor's preview pane. A document rendered on a real browser page gets all of it for free.

An editor is for editing. Opening a whole workspace to read one file is heavy, and the preview sits in a pane wired for writing, not reading. In the browser, reading a Markdown file is a double-click: it opens in a tab, next to the issue tracker, the spec, and the pages it links to — where the rest of your reading already happens.

Not everyone has an editor. Hand a folder of notes to a teammate, a reviewer, or future-you on another machine, and "double-click the README" is the whole onboarding. No project setup, no extensions to configure, no editor at all.

What the existing extensions get wrong

The browser extensions that render Markdown mostly do it inside their own viewer pages — where no other extension can reach, so the reading toolkit above goes quiet. And the one extension that did offer folder browsing put it behind a subscription with a sign-in, for a tool whose whole job is reading local files.

So this is the product, in three commitments:

The document renders in place, on the page it was asked about. Not in a viewer app, not in an extension page — on the file:// or web page itself. That single architectural choice is why translation extensions, highlighters — anything that works on pages — keep working on top of your documents. It's not a compatibility patch; it's the foundation.

The folder sidebar is free, forever, with no account. Point the extension at a folder and it becomes a reading room: a tree you can walk, a marker on folders that actually contain Markdown, search across every file inside, recents and pins, an outline that follows your scrolling — all arranged in panels that dock, stack and split like an editor's, and remember how you left them.

Nothing about you leaves your machine. No account, no telemetry, no server. Diagrams (Mermaid) and math (KaTeX) render from code bundled inside the extension. The permission model is deliberately boring: file access is the browser's own switch, site access only ever engages when a site you allowed serves an actual Markdown document, and the extension never asks to read your browsing history.

Around those three sit the comforts: six palettes, each complete in light and dark; reading dials for size, leading and measure, plus four colours you can set by hand; auto-reload while an AI session is still writing the file; a raw-text toggle; document tabs; an interface in ten languages.

It ships for Chrome and Edge first. If you review Markdown for a living — or you've just always wanted your .md files to open like documents instead of source code — install it and drop a file in. It's two minutes, and the folder feature that's a subscription elsewhere is simply there.