Celsus

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.