Celsus
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10+
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About this app
Celsus is a PDF reader built around one idea: your reading should be measurable and your notes should be organized.
READING SPEED TRACKER
Celsus automatically tracks how long you spend on each page and calculates your reading speed in pages per minute. Pause and resume the timer whenever you need. Over time, you'll see exactly how fast you read and how many hours you've put into each book.
MY NOTES — EVERYTHING IN ONE PLACE
Every highlight, handwritten note, drawing, and photo you take while reading is saved together in a single file for each book. Tap "My Notes" on any book card to open your complete reading journal instantly.
HIGHLIGHTS & ANNOTATIONS
Select any text with a tap to copy, highlight, or add a note. Long-press a highlight to remove it. All annotations are preserved between sessions.
DRAWING & PHOTO ATTACHMENTS
Sketch directly on pages with the drawing tool, or attach a photo from your camera or gallery. Drawings and photos are saved alongside your text highlights and notes.
OCR TEXT RECOGNITION
Celsus can scan scanned or image-based PDFs and extract text using on-device OCR. No internet connection required — all processing happens locally on your device.
FULL-TEXT SEARCH
Search for any word or phrase across the entire book. Results show the page number and a text preview for quick navigation.
READING OVERVIEW
See all pages of your book as thumbnails. Tap any page to jump to it instantly.
THEMES
Eight carefully designed color themes — Warm, Mocha, Forest, Cosmic, Breeze, Slate, Rose, and Midnight — to match your reading environment.
PRIVACY FIRST
Celsus does not collect any personal data. All your books, notes, and reading history stay on your device.
READING SPEED TRACKER
Celsus automatically tracks how long you spend on each page and calculates your reading speed in pages per minute. Pause and resume the timer whenever you need. Over time, you'll see exactly how fast you read and how many hours you've put into each book.
MY NOTES — EVERYTHING IN ONE PLACE
Every highlight, handwritten note, drawing, and photo you take while reading is saved together in a single file for each book. Tap "My Notes" on any book card to open your complete reading journal instantly.
HIGHLIGHTS & ANNOTATIONS
Select any text with a tap to copy, highlight, or add a note. Long-press a highlight to remove it. All annotations are preserved between sessions.
DRAWING & PHOTO ATTACHMENTS
Sketch directly on pages with the drawing tool, or attach a photo from your camera or gallery. Drawings and photos are saved alongside your text highlights and notes.
OCR TEXT RECOGNITION
Celsus can scan scanned or image-based PDFs and extract text using on-device OCR. No internet connection required — all processing happens locally on your device.
FULL-TEXT SEARCH
Search for any word or phrase across the entire book. Results show the page number and a text preview for quick navigation.
READING OVERVIEW
See all pages of your book as thumbnails. Tap any page to jump to it instantly.
THEMES
Eight carefully designed color themes — Warm, Mocha, Forest, Cosmic, Breeze, Slate, Rose, and Midnight — to match your reading environment.
PRIVACY FIRST
Celsus does not collect any personal data. All your books, notes, and reading history stay on your device.
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Safety starts with understanding how developers collect and share your data. Data privacy and security practices may vary based on your use, region, and age. The developer provided this information and may update it over time.
No data shared with third parties
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No data collected
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What’s new
Add text notes to your drawings! A pencil icon appears beside each annotated sketch — tap it to view or edit your note. Reading stats improved: pages now show grouped time and speed (min/pg).
