Whio Press Kit
Read technical books comfortably.
App name
Whio: EPUB & PDF Reader
Developer
Developer location
Alexandra, New Zealand
Launch date
Version 1.0: available on the App Store
Key contact
Platform requirements
iOS 26.0 and higher
iPadOS 26.0 and higher
Pricing (in USD)
Free to download. Whio Unlimited unlocks reading your own books.
Whio Unlimited: subscription at $4.99/week or $39.99/year, or $89.99 once.
Check the local App Store for pricing in other currencies.
App description
Whio is an EPUB and PDF reader for technical books on iPhone and iPad, including iPhone Duo, with a focus on readability and accessibility. With support for code examples, diagrams, and detailed explanations, it gives you clear syntax highlighting, illustrations to explore, and independent reading preferences for text and code.
So many technical books and papers are only available as PDFs, and they're really hard to read on a phone. Whio turns them into reflowable books, so the text adapts to the screen while code keeps its formatting and tables, diagrams, and equations stay intact. It works with scanned PDFs too. Once imported, a PDF gets the same reading customization and accessibility support as any EPUB.
Whio offers high-contrast themes, softer contrast, and tinted backgrounds for different reading needs. Each theme includes light and dark variants, with the option to follow your device's appearance. Code has its own font, size, and weight settings, so you can make examples larger or bolder while keeping the prose as you like it.
For additional support as you read, there are two optional reading aids: letter distinction and the reading guide. Letter distinction adds space between letters that can blend together and subtly varies their emphasis to help distinguish letter shapes and word boundaries. A reading guide lets you underline the line you're following or keep a few lines in focus while dimming the surrounding text.
There is search across the whole book, and a Notebook where you can keep bookmarks, highlights, and notes for both text and code. Whio also comes with three short illustrated books written for it, so there's something to read as soon as you open the app.
About the developer
Whio is 100% indie made, created by Natalia Panferova, a former Apple engineer, Apple Entrepreneur Camp alumna, and technical book author based in New Zealand.
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