--- title: Open Book Touch | daily.dev description: Open Book Touch is a crowdfunded, fully open source e-reader built around a 4.26-inch front-lit e-paper touchscreen. Powered by an ESP32-S3 with Wi-Fi and... canonical: https://daily.dev/posts/open-book-touch-dhihdpvr0 twitter:card: summary_large_image twitter:site: @dailydotdev og:type: website og:site_name: daily.dev og:title: Open Book Touch | daily.dev og:description: Open Book Touch is a crowdfunded, fully open source e-reader built around a 4.26-inch front-lit e-paper touchscreen. Powered by an ESP32-S3 with Wi-Fi and... og:url: https://daily.dev/posts/open-book-touch-dhihdpvr0 og:image: https://api.daily.dev/og/posts/DHiHDPVr0.png og:image:alt: Open Book Touch og:image:width: 1200 og:image:height: 630 og:locale: en --- > ## Documentation Index > Fetch the complete documentation index at: https://daily.dev/llms.txt > Use this file to discover all available pages before exploring further. # Open Book Touch **[Hacker News](https://daily.dev/sources/hn)** · 10 min read · 1 upvotes · 0 comments ## Summary Open Book Touch is a crowdfunded, fully open source e-reader built around a 4.26-inch front-lit e-paper touchscreen. Powered by an ESP32-S3 with Wi-Fi and Bluetooth LE, it runs a custom C++ UI framework called Focus (MIT-licensed, open-sourced today), uses ESP-IDF and FreeRTOS, and manages library metadata with SQLite. It supports EPUB and plain text files from a microSD card, renders dozens of writing systems via GNU Unifont, and features adjustable warm/cool frontlighting. The hardware is user-repairable with a swappable battery and snap-fit 3D-printed enclosure. All schematics, board files, CAD, and firmware will be released when units ship. Targeting early 2027 delivery, the campaign runs through August 20, 2026. ## Full article daily.dev links to this article rather than hosting it. Read it at the original source: ## Questions this post answers ### What microcontroller and software stack does the Open Book Touch e-reader use? It is built around a dual-core ESP32-S3 with Wi-Fi and Bluetooth LE, running firmware built on ESP-IDF and FreeRTOS instead of Arduino, with SQLite managing the book library's metadata. It also supports Arduino and CircuitPython for anyone who wants to use it as an e-paper development board. _Developers evaluating ESP32-S3 firmware stacks can track hands-on builds like this via daily.dev._ ### What is the Focus C++ application framework used in Open Book Touch? Focus is a bespoke, platform-agnostic C++ application framework built in the spirit of NeXTSTEP's AppKit and Apple's UIKit, providing view controllers, a touch-and-gesture system, on-screen widgets, and an on-screen keyboard. It works behind a swappable display driver, running the same UI code on anything from a large touchscreen to a small monochrome LCD with a joystick, and it is released as open source separately from the hardware. _Anyone building embedded UI on constrained displays can follow open source frameworks like Focus on daily.dev._ ### How long does the battery last on the Open Book Touch e-reader? With the frontlight off, testing showed about a week of continuous reading and well over a month in standby, using at minimum an 800 mAh battery, with a possible 1200 mAh cell if it can be reliably sourced. Battery life shortens as the frontlight brightness increases, and the battery is user-swappable. _Readers weighing e-reader battery tradeoffs can keep tabs on projects like this via daily.dev._ ## Similar posts on daily.dev - [A DRM-free, WiFi-connected 4.26-inch open-source hardware e-reader \(Crowdfunding\)](https://daily.dev/posts/a-drm-free-wifi-connected-4-26-inch-open-source-hardware-e-reader-crowdfunding--00gfvwppm) · CNX Software · 1 upvotes · 0 comments - [Free Ink · An open ecosystem for e-readers](https://daily.dev/posts/free-ink-an-open-ecosystem-for-e-readers-6s2tt8m4j) · Hacker News · 0 upvotes · 0 comments - [Pocket-Sized E-Ink Gets A Firmware Upgrade](https://daily.dev/posts/pocket-sized-e-ink-gets-a-firmware-upgrade-8gdncnm7o) · Hackaday · 0 upvotes · 0 comments - [Xteink X4 Pro review](https://daily.dev/posts/xteink-x4-pro-review-nx6i5silr) · Lobsters · 0 upvotes · 0 comments --- Tags: [#hardware](https://daily.dev/tags/hardware), [#iot](https://daily.dev/tags/iot), [#embedded](https://daily.dev/tags/embedded), [#sqlite](https://daily.dev/tags/sqlite) [View this post on daily.dev](https://daily.dev/posts/open-book-touch-dhihdpvr0) ```json {"@context":"https://schema.org","@graph":[{"@type":"Organization","@id":"https://daily.dev/#organization","name":"daily.dev","url":"https://daily.dev","logo":{"@type":"ImageObject","url":"https://daily.dev/apple-touch-icon.png","width":180,"height":180},"sameAs":["https://twitter.com/dailydotdev","https://github.com/dailydotdev","https://www.linkedin.com/company/daily-dev-ltd"]},{"@type":"WebSite","@id":"https://daily.dev/#website","url":"https://daily.dev","name":"daily.dev","publisher":{"@id":"https://daily.dev/#organization"},"potentialAction":{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https://daily.dev/search?q={search_term_string}"},"query-input":"required name=search_term_string"}}]} {"@context":"https://schema.org","@type":"TechArticle","headline":"Open Book Touch","url":"https://daily.dev/posts/open-book-touch-dhihdpvr0","mainEntityOfPage":{"@type":"WebPage","@id":"https://daily.dev/posts/open-book-touch-dhihdpvr0"},"datePublished":"2026-07-18T01:38:18.259Z","dateModified":"2026-09-13T20:17:26.904Z","description":"Open Book Touch is a crowdfunded, fully open source e-reader built around a 4.26-inch front-lit e-paper touchscreen. 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