productivity

Reveal Sheet

Cover answers in photos or diagrams, reveal them to study, and save an editable sheet or a self-contained HTML lesson.

Local processing

About your filesFiles and content selected in this tool are processed in your browser and are not uploaded to a Browser Kitty backend.

Operation demo See the basic workflow in a short video.

About this tool

Reveal Sheet turns images that already contain answers—such as labeled diagrams, photographed worksheets, screenshots, and notes—into interactive study material. Drag over an answer to place a cover, try to recall it, then reveal it to check.

Study by revealing covers in any order or use a guided one-question-at-a-time flow with Recalled / Review again self-assessment. Save editable JSON or export a single HTML lesson containing the images and study player. You can reopen either format later. Image and lesson processing stays in the browser.

Good for

Hide labels on a map or science diagram and reveal them after recalling the answer
Turn a photographed worksheet or notebook page into a cover-and-reveal lesson
Group related answers into one question and review them one at a time
Save a lesson as one HTML file to study or share without an ongoing connection
Organize images into multiple pages and return later to add or correct questions

What it can do

Key capabilities available in this tool.

Import JPEG, static PNG, or static WebP images and drag over answers to create covers
Move, resize, duplicate, delete, and recolor covers with Undo / Redo
Group several covers into one question and keep auxiliary hints covered during study
Choose free reveal or guided one-at-a-time study with Recalled / Review again after viewing each answer
Rename, describe, and reorder multiple pages; edit a question during guided study and return to it
Export and reimport editable .reveal.json files or self-contained .reveal.html lessons with images and a study player
Use dedicated Create / Study / Save screens on phones, with Japanese / English UI and keyboard support
Process images locally; optional work recovery and study-progress storage are separately OFF by default

How to use

Choose Add images and import JPEG, static PNG, or static WebP. On desktop, drag and drop or image paste also works.
Drag over an answer to create a cover. Move, resize, recolor, duplicate, or delete covers as needed.
Optionally use Reveal together to make several covers one question, or Keep covered while studying for auxiliary areas.
If using multiple pages, name, describe, and reorder them, and adjust the question order.
Open Study and choose Reveal freely or One at a time. Guided study lets you rate Recalled or Review again only after seeing the answer.
Use Edit this question to make corrections during guided study, then return to the study screen.
Export .reveal.json for later editing or .reveal.html for a portable, self-contained lesson. Both can be reopened.

Supported

Images: JPEG, static PNG, and static WebP, normalized internally to orientation-fixed PNG.
Cover editing: create, move, resize, duplicate, delete, and change colors, with Undo / Redo.
Study modes: free reveal and guided questions. Group multiple covers or keep auxiliary areas hidden during study.
Multiple pages: edit names, descriptions, page order, and question order. On phones, page cards are a horizontal carousel.
Export: re-editable .reveal.json or self-contained .reveal.html with embedded images and study player; both support reimport.
Count limits: 30 pages per lesson, 1,000 covers in total, 200 covers per page, and 1,000 questions.
Input limits: 20 MiB per image, maximum 8,192 px per side and 16 million pixels, 64 MiB combined lesson images.
Browser targets: Chrome / Edge, with Japanese / English UI, mobile layouts, and keyboard operation.

Limitations and notes

Covers are for memorization, not redaction. Original image pixels and answers remain in editable files and lessons. Do not use covers to remove confidential information.
GIF, animated PNG/WebP, SVG, HEIC/HEIF, AVIF, and direct PDF input are unsupported. Convert PDF pages to supported images first.
There is no OCR or automatic answer detection. You position covers and rate recall yourself.
Study results are not exported in .reveal.json or .reveal.html. Local work recovery and study-progress storage are independent settings, both OFF by default.
Lessons embedding many images can be large. Browser storage may be cleared or unavailable, so export important materials to files.
Physical iPhone/Android and Safari/Firefox testing is not claimed as completed; file sharing and saving vary by device.

Frequently asked questions

Which images can I turn into study sheets?

You can import JPEG, static PNG, or static WebP. Add a diagram, worksheet, or notes photo and drag over the answers. PDF is not a direct input format.

Can I share a sheet with someone else?

Yes. Export a .reveal.html file containing the images and study player. The recipient can open it in a supported browser. Review the contents before sharing because the original images remain embedded.

Does covering an answer permanently remove it?

No. Covers are reversible and the original pixels remain in the lesson. This is not a secure redaction tool.

Can I edit a sheet later?

Yes. Reopen an exported .reveal.json file or a compatible .reveal.html lesson. When importing HTML, the app validates the embedded data without running imported scripts.

Is study progress saved automatically?

Not by default. You can separately enable local work recovery and local progress storage. There is no device-to-device sync, and exported lessons do not include study results.

Offline version and source code

The standalone app and its exported lesson HTML are self-contained. The runtime uses no external CDN, API, or analytics and sets CSP connect-src 'none'. Opening the hosted app requires the initial HTML download, but imported images and lesson data are not uploaded.

View source on GitHub