I built a native Mac Markdown editor solo, with zero dependencies. It launched on Product Hunt today

Hi DEV! I'm Pedro, and for the past months I've been building Coffee, a Markdown editor for the Mac, on my own. It went live on Product Hunt today, so here's what it is and a few things I learned building it.

What it does

• Plain files. Every note is a .md file in a folder you choose. No database for your writing, no import step, and any other editor can open the same folder (an Obsidian vault works as it is).
• Answers beside the line. Write 20% of 50, $30 in EUR, Tokyo time or half of 175 and the answer appears next to the line, without going into your file.
• Maths and Mermaid, drawn natively. No web view: TeX and Mermaid diagrams are rendered by the app itself.
• Review every AI edit. When Claude, Cursor or anything else changes a note's file, Coffee lays out every change and you keep or undo each one.
• MCP, off by default. AI apps can read and write your notes over MCP, but only once you turn it on.

How it's built

• Swift 6.2 and SwiftPM, macOS 15 and later.
• Zero third-party dependencies. The Markdown parser, the Mermaid and TeX renderers and the calculator are all written for the app. Search runs on the system's SQLite.
• Separate small executables for the MCP server, Quick Look and the updater, so each one does one job.

Writing my own Mermaid renderer sounded like a bad idea at first, but it means diagrams appear instantly, look like the rest of the app and work offline.

What I learned on launch day

The launches above mine came in with three to five times more Product Hunt followers than I had. Followers before the day matter far more than anything you do on the day. If you're planning a launch, start collecting them weeks earlier.

Try it

14 days free, no card or account: coffeetext.app

It's in its final hours on Product Hunt, and I'd love honest feedback there or here: Coffee on Product Hunt

What would make you switch from your current Markdown editor?