OpeningBook vs Kawn

OpeningBook is a clean, offline reference and trainer for chess openings. BROWSE EVERYTHING • Thousands of named openings and variations, organized by ECO volume (A–E), family, and line — sourced from the open Lichess openings database. • Step through any line move-by-move on a real, playable board. • Read key ideas and classic traps for the major openings. SEARCH & FILTER • Find any opening by name, ECO code, or move sequence. • Filter by line length with a simple move-count slider. TRAIN YOUR REPERTOIRE • Add lines to your training set as White or Black. • Drill them in a play-your-side-vs-app loop. • Spaced repetition brings each line back for review at the right time. 100% offline. No account, no ads, no tracking.

Kawn is an encyclopedia of the whole universe, written for curious minds in English and Arabic. Meet a snow leopard, fly past the rings of Saturn, then swing a pendulum on the Moon - all in one app. LIVING WORLD - Explore hundreds of thousands of animals and plants with photos, English and Arabic names and family trees - See conservation status, where each species has been recorded and its closest relatives - Life Near You shows the species people have recorded around you SPACE - A 3D solar system you can fly through, with real data for every planet and major moon - The astronomy picture of the day and a sky archive going back to 1995 - The International Space Station live on a map and upcoming rocket launches - Asteroids passing Earth and today's space weather PHYSICS LABS - Live simulations of pendulums, projectiles, gravity and orbits, waves, lenses and electric fields - Change a value and watch the result, with the equation behind it SCIENCE LIBRARY - The great laws of physics with worked examples - The fundamental constants of nature - Scientists across history, including the scholars of the Islamic Golden Age - A timeline of discovery VIDEO LIBRARY - Every category has its own video hub with themed collections, from big cats and carnivorous plants to black holes and quantum physics - Documentaries and explainers in Arabic and English from trusted science channels, played with YouTube's own player - Keep a Watch later list of the videos you want to see LEARN AND PLAY - Daily quizzes, challenge mode, explorer ranks and badges - Save favorites and listen to articles read aloud - Optional Sign in with Apple keeps your progress on all your devices Kawn Pro is a single one-time purchase that unlocks every physics lab, the full video library with Watch later, challenge mode, Life Near You and the full sky archive. No subscription. Content comes from iNaturalist, Wikipedia, NASA, JPL, NOAA and The Space Devs, and every photo is shown with its credit and license.