i vs Red Sheet
Price, ratings, monetisation and update history for both apps, side by side — with what reviewers say about each.
i
This app allows users to hide text in study materials using a filter, mimicking a red sheet for effective memorization. It supports photos and PDFs, enabling studying anytime, anywhere with just a smartphone.
- Hide text with red filter effect
- Study photos and PDFs
- Add check marks for progress
- Efficient study with navigation
- Use anytime, anywhere
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【Ranked #1 in the Education category (free)】 【Over 1 million downloads】 Featured in various media: ・Fuji TV "Minna no News (2017/2/9)": Red-sheet generation stunned! A revolution in memorization methods ・Benesse Manapla: Make high school life even more fun! 3 useful apps ・Nikkei Trendy Net "TODA Satoru’s Deep-Dive Report on Gadgets": How working adults use iPad and handwriting apps for learning i-Memorization Sheet is an app for memorization study that hides words, sentences, dates, etc. using a filter so you can study them. The app uses image analysis to reproduce the same effect as using a real red filter. Therefore, red text in reference books can be hidden simply by photographing it. You can also import entire reference books by converting them to PDF. With just an iPhone, you can study anytime, anywhere. 【Benefits of i-Memorization Sheet】 - Study anytime, anywhere—e.g., easily memorize with one hand on the train. - Carry as many pages as you want just by bringing your smartphone. - Disappears better than real red sheets. All reddish colors are hidden. Green is fine if it's a fluorescent highlighter. - You can add check marks anywhere. Double-tap where you want to place a mark. There is also a function to jump to the next check mark, making studying very efficient. 【Supported materials】 - Photos and PDFs can be used. 【Pricing】 You can use the app for free for up to 10 pages in total. If you want to use more files/pages, please purchase an add-on. Ads are displayed, but purchasing the add-on can disable them.
Red Sheet
Create and study flashcards from your PDFs, notes, and images. This app lets you hide and reveal text to transform study materials into interactive flashcards for faster memorization. Supports various import options and flexible study tools.
- Create flashcards from PDFs
- Import from note apps and cloud storage
- Hide and reveal text for study
- Create flashcards from photos and images
- Vocabulary and word list flashcards
- One-tap show/hide for quick review
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◆ All-in-One PDF Memorization App with Red Sheet Study Turn your PDFs, notes, textbooks, handouts, and images into powerful study materials. This app helps students memorize faster by hiding and revealing important parts of their own documents. Import PDF files, photos, scanned notes, class handouts, worksheets, and study materials, then create memorization blocks directly on the page. It works like a digital red sheet, flashcard maker, and PDF study tool in one simple app. ◆ PDF Memorization Made Simple ・Import PDF files and study directly from the page ・Hide words, definitions, formulas, diagrams, and answers ・Tap to reveal hidden areas while reviewing ・Use red sheet style memorization on PDF pages ・Study textbooks, school handouts, exam materials, and notes ・Create your own PDF memorization notebook If you already study with PDFs, this app turns them into active memorization tools. ◆ Red Sheet Style Study for PDFs and Images Use memorization blocks to cover the parts you want to remember. Place blocks over text, formulas, diagrams, definitions, answers, or explanations. ・Hide text like using a red sheet ・Reveal answers by tapping ・Create blocks anywhere on a PDF or image ・Adjust block size by dragging the edges ・Change the color and style of blocks ・Use blocks for notes, textbooks, worksheets, and scanned documents This is useful when you want to memorize from your own materials without rewriting everything into separate flashcards. ◆ Smooth Vertical Review for Memorization Review multiple PDF pages and images smoothly. Vertical scrolling makes it easy to study long documents, like moving a red sheet from top to bottom. ・Scroll vertically through study pages ・Review many PDF pages at once ・Memorize photos and handouts continuously ・Swipe between pages and cards ・Add more images when needed ・Study at your own pace Useful for test prep, school study, certification exams, language learning, and daily review. ◆ Useful Study Tools ・One-tap show and hide for fast review ・Multiple memorization blocks for one page ・Auto-align blocks for cleaner layouts ・Zoom in with two fingers to study small text ・Hidden areas stay aligned even when zooming ・Add memo text to support memorization ・Hide memo text for self-testing ・Organize study decks by title or subject Create separate study materials for English, science, history, math, medical terms, law, certification exams, or any subject that requires memorization. ◆ Great For ・Students preparing for tests and exams ・PDF study and textbook review ・Vocabulary memorization ・Language learning ・Science, history, math, and social studies ・Certification exam preparation ・Medical, legal, and technical study ・People who want a simple flashcards maker ・Students who use GoodNotes, notes apps, or PDF files ・Anyone who wants to memorize from their own materials ◆ How to Use 1. Import a PDF file, photo, or image 2. Place memorization blocks over the parts you want to hide 3. Tap to reveal the answer while studying 4. Repeat until you can remember it 5. Organize your materials by subject and review again ◆ Why This App Is Different This app focuses on PDF memorization and red sheet style study. You do not need to recreate every page from scratch. Use your own PDFs, notes, handouts, images, and textbooks as they are, then hide only the parts you want to memorize. It is a simple way to turn everyday study materials into flashcard-style memorization tools. ◆ Recommended If You Want ・A PDF study app for memorization ・A flashcards maker from PDFs ・A red sheet style study app ・A way to memorize school notes and handouts ・A simple tool for exam preparation ・A study app that works with your own materials ・A faster way to hide and reveal answers Start studying your own PDFs, notes, and images with red sheet style memorization. Make your study materials easier to review, repeat, and remember. Terms of Service https://hidevoicy.com/en/tos Privacy Policy https://hidevoicy.com/en/privacy
Screenshots
Verdict
i and Red Sheet both sit at 4.2 stars, but that hides the real split: 80% of Red Sheet's written reviews are positive against 43% of i's. Red Sheet also leads on device support (4 vs 2) and iOS requirement (13.0 vs 18.0). On price, rating, ratings volume and update cadence 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. i sells 10 one-off in-app purchases and Red Sheet sells 7 in-app purchases, starting at $2.99 per month. Whichever you choose, the download price is not the number that matters.
On the App Store both sit at effectively the same score — 4.2 for i against 4.2 for Red Sheet. Both are backed by a comparable volume of ratings — 10 and 5 respectively. Written reviews are what separate them: 43% of i's written reviews are positive against 80% of Red Sheet's.
i ships an update every 6 days, Red Sheet every 3 days. Both last shipped on September 22, 2026.
| Parameter | i | Red Sheet |
|---|---|---|
| Price | Free | Free |
| Rating | 4.2 (10 ratings) | 4.2 (5 ratings) |
| Positive reviews | 42.9% of reviews | 80.0% of reviews — better |
| Number of ratings | 10 — better | 5 |
| Update frequency | Every 6 days | Every 3 days — better |
| Ads | Yes | Yes |
| In-app purchases | Yes | Yes |
| Monetization | Free with in-app purchases | Free with in-app purchases |
| Devices | iPhone, iPad | iPhone, iPad, iPod, Mac — better |
| Requires iOS | 18.0 | 13.0 — better |
| Further details — not scored | ||
| Size | 67 MB | 193 MB |
| Age rating | 4+ | 4+ |
| Developer | BrainApp LLC | Foodmenu.world Inc. |
Customer experience
i
Red Sheet
In-app purchases
i
- i-Memorize Sheet Remove ADs Option$0.99
- imc00010$0.99
- imc00020$0.99
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- i-Mem-Contents imc00030$0.99
- i-Mem-Contents imc00040$0.99
- i-Mem-Contents imc00010$0.99
- i-memorize Sheet File-Limit release add-on$2.99
- i-memorize Sheet PDF page-Limit release add-on$4.99
- Pro licence(campaign)$5.99
- i-memorize Sheet Limit release add-on$6.99
Red Sheet
- Monthly Special plan$2.991 Month
- Monthly Super Saver Plan$2.991 Month
- Monthly Value Plan$3.991 Month
Show 4 moreShow fewer
- Basic Plan$5.991 Month
- 3 Month Plan - V 3.1.5 needed$9.993 Months
- Half year plan (Sale)$17.996 Months
- Half year plan - V2.9.0 needed$22.996 Months









