Chinese Oracle Jiaguwen is an iOS and Android app for people curious about Chinese characters, ancient scripts and calligraphy. It presents old character forms, visual structure explanations, comparisons with modern characters and tracing practice. The collection contains roughly 800–1,000 characters. A few dozen are free to use; additional content requires in-app purchases.
App Store: https://apps.apple.com/app/id6743118917
Google Play: https://play.google.com/store/apps/details?id=com.ijiagu.android