Your everyday files, the way they should look.
hYYa ink opens the files developers and writers deal with every day — .md, .json, .yaml, .csv, .mmd — and renders them the way they're meant to look, instead of as walls of raw text. No IDE to boot up, no cloud, no account. Just tap a file and read it. Built natively for Mac (Apple Silicon + Intel), it opens in milliseconds and never sends your files anywhere.
Many formats, one calm reading view.
Markdown, rendered
Headings, bold/italic, links, lists, code blocks and quotes, in a clean reading layout.
JSON & YAML trees
Collapsible, color-coded by type — structure at a glance.
CSV & TSV grids
Spreadsheets as tidy tables, with the header row highlighted.
Live Mermaid diagrams
Flowcharts render instantly, fully offline.
Quick Look built in
Press Spacebar in Finder to preview any supported file, beautifully.
Opens by double-click
Registers your file types so they just open.
Native, fast, private
SwiftUI, opens in milliseconds, zero tracking, zero data collection — works with no internet.
Universal & modern
One app for Apple Silicon and Intel, macOS 14 Sonoma and later.
One light app that respects your files.
Other tools make you choose: a heavy IDE, a single-format viewer, or a cloud note app that imports your files into its world. hYYa ink is one lightweight, local-first app that renders many formats natively — and respects that the files are yours.
Free to view every supported format.
The core app is free — no subscription, ever. An optional one-time Pro unlock (a single purchase, not a subscription) adds editing and advanced formats, plus optional AI assistance.
Coming soon
Planned, not yet shipping — here's what we're building next.
Frequently Asked Questions
What is hYYa ink?
hYYa ink is a native macOS app that opens the files developers and writers deal with every day — Markdown, JSON, YAML, CSV and Mermaid — and renders them the way they're meant to look, instead of as walls of raw text. No IDE to boot up, no cloud, no account: just tap a file and read it.
Which file formats does it support?
Today hYYa ink renders Markdown (.md), JSON (.json), YAML (.yaml/.yml), CSV and TSV (.csv/.tsv), and Mermaid diagrams (.mmd). Markdown shows headings, bold and italic, links, lists, code blocks and quotes; JSON and YAML become collapsible, color-coded trees; CSV and TSV become tidy tables; and Mermaid flowcharts render live and fully offline.
Is it free?
Yes. The core app is free to view every supported format, with no subscription. An optional one-time Pro unlock adds editing and advanced formats, plus optional AI assistance — but viewing is completely free.
Does it work offline?
Yes. hYYa ink works with no internet connection at all. Everything — including live Mermaid diagram rendering — happens locally on your Mac. Your files never leave your device.
Is my data private?
Completely. hYYa ink is local-first with no accounts, no tracking, and zero data collection. It never sends your files anywhere. Your files never leave your Mac.
Which Macs does it run on (Apple Silicon / Intel, macOS 14+)?
hYYa ink is a universal app that runs on both Apple Silicon and Intel Macs, on macOS 14 Sonoma and later.
Does it work with Quick Look?
Yes. hYYa ink includes a Quick Look extension — press the Spacebar on any supported file in Finder to preview it, beautifully rendered, without opening the app.
Can I edit files?
Viewing every supported format is free today. In-place editing is coming soon as part of the optional one-time Pro unlock.
What's coming next?
Planned additions include in-place editing; support for LaTeX, Typst and Jupyter; diff and log viewers; more data formats; opt-in AI help (on-device and cloud); and iPhone and Android versions. These are on the roadmap and clearly labelled as coming soon.