A markdown viewer for macOS that opens instantly.
Double-click a .md file and it renders. Editing is there when you want it, one keystroke away, but reading comes first. No vault, no account, no sync. It opens a file.
The next document opens in about 47 milliseconds
More than 12 times faster than the first one, and the reason is worth a sentence.
MDView keeps a rendering engine warmed up in the background after the first document. Opening the second one does not start anything — it hands the text to something already running. That is the whole trick, and it is why reading a folder full of specs feels like flipping pages rather than launching an app.
Measured on 2026-08-31 over five runs, median.
What it renders
GitHub-flavoured markdown, syntax highlighting, task lists, footnotes and tables — plus diagrams and mathematics, both drawn on your Mac with no network call.
Read first, edit when you want
Press Option-Command-Return and the source comes up beside the rendering. The preview follows shortly after you stop typing, and the two panes scroll together — interpolated between blocks, not snapping.
- Find across both panes with ⌘F, including regular expressions, whole-word and case options. Because the source and the rendering genuinely contain different text, the count tells you both when they differ.
- Print, Export as PDF, Copy as Rich Text — diagrams and equations survive as images, so pasting into Mail or Pages looks like what you saw.
- A Format menu with the shortcuts already in your fingers — ⌘B, ⌘I, ⌘K — plus headings, lists, quotes, code blocks, tables and rules. Pressing bold twice removes it again, and turning a bullet list into a numbered one replaces the marker instead of stacking it.
- Live reload — edit the file in another editor and the view follows, but never over your unsaved work.
- Open Recent, Revert To, Duplicate — the standard macOS document behaviours, where you expect them.
CSV files open too
The other file type that is everywhere in this work and awkward to just look at.
Open a .csv and it becomes a readable grid: headers taken from the first row, numeric columns right-aligned, columns you can resize. Correct a cell in place, add or delete rows and columns, then press ⌘S — CSV files are not autosaved, deliberately, because a stray keystroke in a grid is much harder to notice than one in a text document.
A row you did not edit is written back byte for byte — its quoting, its padding, its line ending — so a one-cell change stays a one-line diff. That matters when your data files live in version control. Large files open immediately, because rows are read only as they are drawn.
It never connects to the network
Nothing to sign into. Nothing leaves your Mac.
This is enforced, not merely intended. The renderer runs under a content policy that permits no outbound connections at all and allows images only from the local document, so remote images, video, audio and tracking attributes in a document are never fetched — opening an untrusted document does not reveal that you opened it. Diagrams and mathematics are drawn on your Mac. There is no account, no sync and no cloud. MDView is sandboxed, and is distributed through the Mac App Store.