CKC OCR vs RainbowSky
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
CKC OCR
This educational tool helps users search for CKC codes and learn Chinese characters. It explains the appearance-based coding system, which encodes characters based on the stroke features of their four corners.
- Search CKC codes for Chinese characters
- Learn Chinese character stroke features
- Understand appearance-based coding system
- View CKC code combinations
- Educational tool for Chinese language teaching
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CKC OCR (縱橫識字) This tool designed by The Education University of Hong Kong (EdUHK) - CKC Centre for the Development of Information Technology in Chinese Language Teaching. Facilitate to search the CKC Code and learn of Chinese characters. For Example, if you search "為", all combinations for the CKC code (including code for variant Chinese character and instant code) will show: 000, 3, 34 and 3400. CKC Chinese Input method is a type of appearance-based coding system. It encodes a Chinese character according to the stroke features of its 4 corners. The sequence is upper left corner, upper right corner, lower left corner and lower right corner (following the shape of the alphabet “Z”) respectively. The strokes and the features of the Chinese character components are classified into 10 groups, represented by 0 through 9. 0 A left-falling stroke or a stroke with left-turning (丿亅). 1 A horizontal stroke or a horizontal rising stroke written from left to right (丨). 2 A vertical stroke or a left slanting stroke (一). 3 A dot or a right-falling stroke (丶 乀). 4 A cross or the radical of “Grass” (十乂卄). 5 The combination of a falling stroke runs through 2 horizontal strokes (≠ キ). 6 A square (口). 7 A corner, 2 upper corners, 2 lower corners or a stroke with right-turning (乚). 8 The shape of the numeral “Eight”(八) in Chinese or its variants (人丷). 9 The shape of the Chinese character which means “Small” (小), its variants and the radical of “Upright Heart”(忄).
RainbowSky
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Your e-books, your pedagogy. Cater your student's need. RainbowOne lets you create your own e-Learning materials and hold a truly interactive and engaging e-lesson. E-books can be easily created and adjusted freely to suit your needs. Our interactive e-lesson equipped with functions which helps you to save time. Exercises can be auto-corrected, and the learning data are analyzed to let you know more about your students’ ability. And the most important is, it is fun! Innovative e-Book Editor: Total Design Freedom We offer 80+ comprehensive tool and 10000+ images for you to tailor-make your e-books. You can start with a free canvas or choose from our templates. With easy drag and drop you can customize anything. Cross-platform lesson: Interact with your students Lesson can be held in a cross-platform environment. You can group your students and hold a competition, voting or discussion. We also provide page-sync, black-out screen and other functions that helps you manage your class. Instant Charts: Know your students well All questions with pre-set answers are instantly corrected. Learning data are automatically collected and analyzed. You can easily find out the learning difficulties of your students. Bookstore with editable e-books Share your knowledge! Here we have a bookstore for you to share your materials in public, and you can read the e-books from the bookstore to get some inspiration, or even download and edit it to suit your needs.
Screenshots
Verdict
The clearest difference is iOS requirement: RainbowSky at 12.0 against CKC OCR's 15.6. On price, update cadence, ads and in-app purchases there is nothing between them.
Scored on Price · Rating · Positive reviews · Number of ratings · Update frequency · Ads · In-app purchases · Monetization · Best chart rank · Devices · Requires iOS
Both are free to download. Neither carries in-app purchases, so what you see is what you pay.
CKC OCR ships an update fortnightly, RainbowSky every 2 weeks. The most recent releases landed on October 4, 2026 and October 6, 2026 respectively.
| Parameter | CKC OCR | RainbowSky |
|---|---|---|
| Price | Free | Free |
| Rating | 3.3 (3 ratings) — better | — |
| Positive reviews | 100.0% of reviews | — |
| Number of ratings | 3 — better | — |
| Update frequency | Fortnightly — better | Every 2 weeks |
| Ads | No | No |
| In-app purchases | No | No |
| Monetization | Free | — |
| Devices | iPhone, iPad, iPod | iPhone, iPad, iPod |
| Requires iOS | 15.6 | 12.0 — better |
| Further details — not scored | ||
| Size | 2 MB | 292 MB |
| Age rating | 4+ | 4+ |
| Developer | Ka Ho Tse | Open Knowledge Association Ltd. |
In-app purchases
CKC OCR
No in-app purchases
RainbowSky
No in-app purchases









