ieo — PDF reader

Sentio Studio

About this app

ieo is named after “이어,” Korean for “continue.” Read your PDFs and pick up where you left off.

READ COMFORTABLY
Scroll through original PDF pages, adjust zoom, or use text view for supported single-column documents. Choose scroll or book view, with one or two pages when space allows. Full-screen reading gives the page more room. Choose a comfortable text size, line spacing and theme.

KEEP YOUR PLACE
Reading positions save on your device. Pin a passage while exploring other pages, then resume automatic recording when you continue reading. Reopen recent cached Drive PDFs quickly and return to the last document when enabled.

USE YOUR OWN GOOGLE DRIVE
Choose which PDFs ieo can access. When connected, supported ieo devices sync reading history through your own Drive app-data folder while online and running. Source PDFs are not modified or uploaded to an operator-run server.

START WITHOUT SIGNING IN
Read the sample or import a PDF from your device. Local documents remain on that device unless you choose Read on other devices and confirm saving a copy to your own Google Drive. The device original is preserved.

YOUR NOTES
Write free notes or attach a note to your reading position. Notes on connected Drive documents sync between supported devices. Search your notes and return to their source passage. Export notes separately as JSON or Markdown.

BACK UP YOUR HISTORY
Export ZIP or JSON reading-history backups and merge them later. Backups contain reading records and short restoration excerpts, not PDF files. Manage PDF copies and delete a library’s reading history separately.

WINDOWS PREVIEW
On your Windows PC, open https://ieo-reader.pages.dev to download the preview installer. No sign-in is needed for local PDFs. Connect the same Google account to continue selected Drive PDFs with your notes and reading position. Check the website for installation requirements.

PLEASE NOTE
Android 10 or later is required. PDFs up to 50 MB are supported. Scans, multi-column pages, tables, formulas and protected PDFs may require original view. Google connection and internet are required for Drive sync; closed-app background sync is not guaranteed.

What’s new

Return to all PDFs more easily when a library search has no results. Layouts now fit narrow screens more reliably.