Support

Yes, completely free. No in-app purchases, no subscriptions. Ads support maintenance and improvements. Visualization screens never show ads: ads are limited to banners at the bottom of the home and explanation screens, plus an occasional full-screen ad when you switch to a different structure.

iOS 17 and later (iPhone / iPad), Android 8.0 (API 26) and later.

Basics (4): Stack / Queue / Array / Linked List
Advanced (4): Tree (binary search tree) / Heap (max heap) / Hash Table (7 buckets, chaining) / Graph (undirected, BFS)

The first information-systems title of the Raku Series, ARURAKU, visualizes algorithms. DATARAKU is its sibling and focuses on data structures. Each structure's explanation notes which ARURAKU algorithms build on it (the heap and heap sort, the graph and BFS / DFS / Dijkstra's algorithm, and so on).

The app follows your device language (Japanese / English). Change your OS language in Settings.

Personalized ads: "Ad settings" on the home screen lets you switch between Allow and Don't allow at any time.
iOS tracking (ATT): Settings → Privacy & Security → Tracking → DATARAKU.
Android advertising ID: Settings → Privacy (or Google) → Ads to reset or delete it.
See the Privacy Policy for details.

This is fixed in version 2.1. Please update to the latest version from the App Store.

Please contact us via the email below. Including reproduction steps, device model, and OS version is appreciated.