GemReader
The private study reader for Android
What it does
Every Android reader either mangles study material or wants an account first. GemReader does neither. Textbooks, lecture PDFs and interactive workbooks in one offline library. Workbook answers save themselves. Highlights become a spaced-repetition deck inside the reader — no export step — and existing Anki decks import. Everything is encrypted on the device. No account, no cloud, no telemetry, no ad SDK. Everything in the app today is free and stays free.
Free study reader for Android. EPUBs, PDFs and workbooks in one library — highlight as you read, then review those highlights as flashcards. Offline, free.
Textbooks, lecture PDFs, and workbooks in one library. Highlight as you read, then study those highlights as flashcards — without exporting anything or leaving the app. The textbook lives one place, the lecture PDFs another, the flashcards somewhere else. You spend the term moving your own notes between them. Textbook in a reader that won't open PDFs. Lecture slides in a PDF app that can't highlight properly. Flashcards in a third app that knows nothing about either. Notes in a fourth. Create an account. Subscribe. Wait for the sync. Read the book on their terms — then watch access expire at the end of term, and your highlights expire with it. You mark up three hundred pages across a…from gemreader.com
Does the same job
all alternatives →- RRReadwise Reader, an all-in-one reading app2022 · readwise.io · ▲326
Hey HN, cofounder of Readwise here. We've been working on this cross-platform reader app for about 2 years, excited to finally share it in public beta. Probably the most notable thing that makes Reader unique is that it supports almost any content type you could want to save/read/highlight: * web pages * emails/newsletters * PDFs * ePubs * twitter threads * youtube videos (with transcripts) * RSS feeds With all of your knowledge content in one place, we built powerful reading and highlighting, as well as a bunch of novel triage/organization features, so you can actually…





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Hi HN, I built Eigendrum, a web tool that solves the 2D wave equation for arbitrary shapes so you can hear what they sound like as drums. How it works: * Solves -∇²u = λu using finite element analysis (Kφ = λMφ) on a triangle mesh. * Validated to <0.1% error against closed-form solutions for circles (Bessel zeros) and rectangles. * Sound model factors in strike location, Rayleigh damping, and mallet width. * Includes Kac drums I & II to demonstrate identical sound spectra from different geometries. * No frameworks, build steps, or dependencies. Repo and tests:…
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Launched alongside, August 2026
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Life & fun · 9d ago · louisabraham.github.io


- SA
Hello HN! I found that picking out plausible but diverse skin tones for my digital art and game development projects was kind of difficult, and I got curious about if there was a way to define a color space that made it easy. I've built a color picker and procedural generation algorithm based on the space as well as a bunch of other fun js features and demos throughout the page that use the equations. If you find it interesting, I have lots of explanations of how I built it and what properties the space has. The methodology might be a bit shaky, but hopefully the result is as helpful for…
Life & fun · Aug 2026 · toneyalexander.github.io


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