hYYa ink

PDF too: add text exactly where you want it, sign by hand, and mark up the page — all on your device.

Stop reading syntax. Start reading documents.

hYYa ink is the universal document engine: it opens the files developers, students, and academics live in — and turns them into beautiful, readable, editable documents instead of walls of raw text. On Mac, iPhone, and iPad.

ONE APP, EVERY FORMAT • Markdown — rendered live, with a formatting toolbar (bold, headings, lists, quotes, links) • JSON, YAML, TOML — interactive collapsible trees you can edit in place • CSV & TSV — a real table, editable cell by cell • Mermaid & Graphviz — diagrams drawn instantly, fully offline • LaTeX — math typeset beautifully • Jupyter notebooks — cells, code, and outputs, cleanly laid out • AsciiDoc, Org-mode, XML, diff, logs — readable at last

EDIT, DON'T JUST VIEW Edit the source and watch the document update. On Mac and iPad, a split view shows source and preview side by side. Edit JSON trees and CSV tables directly in the preview — hYYa ink writes valid syntax back for you. Full undo, native editing.

PDF — VIEW, ADD TEXT, SIGN & MARK UP Open any PDF as a real document. hYYa ink never hunts for fields or boxes — tap the exact spot you want and type, then drag to fine-tune. Sign by hand in black or blue ink, and resize, rotate and place your signature. Mark up any page by hand with Apple Pencil or your finger, using the system tool set. Everything stays adjustable while the document is open, and nothing is written until you save: “Save copy” writes a new PDF and leaves the file you opened untouched. It all happens on your device.

BRING YOUR OWN AI Connect any OpenAI-compatible provider — OpenRouter, OpenAI, Groq, Together AI, or your own custom endpoint. Then Explain, Summarize, Reformat, Fix errors, or generate Mermaid diagrams from your document. Your key stays in the device Keychain; only the open document is sent, and only when you ask.

PRIVATE BY DESIGN. BEAUTIFUL BY DESIGN. No accounts. No tracking. No data collection. Everything renders offline on your device — the only network calls are the AI requests you explicitly make to your own provider. Your documents never leave your device unless you ask.

FREE TO READ, PRO TO EDIT Reading and previewing every format is free forever — so are Export to PDF and Print. A 7-day full trial unlocks everything; a single one-time purchase keeps editing and AI yours forever — across Mac, iPhone, and iPad.

On Mac, Quick Look works too: press Space in Finder for a beautiful preview.

From hYYa — more than apps. Companions you can trust.