PIE — PDF & Image Editor

PIE is an offline PDF and image editor for Android and iOS, built with React Native. It edits the existing text in PDFs and in screenshots or photos, matches the original font and layout as closely as possible, and does all processing on the device. Nothing is uploaded, there is no account, and there is no cloud OCR or AI image generation.

Features

PDF

• Open, render, zoom (with sharp re-rendering of the visible area) and pan, including rotated pages
• Select existing text like Google Drive: long-press a word, then drag the handles to extend the selection character by character
• Edit, replace and delete existing text, including text inside nested Form XObjects; the rest of the line closes up or makes room
• Add text as movable, resizable text boxes (font, size, bold/italic, colour, alignment)
• Highlight, underline and strikethrough in a choice of colours; ink and shapes; signatures; images
• Pages: rotate, reorder, duplicate, insert blank, delete; merge PDFs; create a PDF from photos
• Find text, copy page text
• Undo/redo, Save, Save a Copy (system file picker), Share
• Every edit is verified by reopening the saved file; a failed edit is reported, never hidden
• The original file is never modified

Images

• Import JPEG/PNG (camera, photo library, files) at original resolution, with EXIF orientation
• On-device OCR: Google ML Kit (Android), Apple Vision (iOS)
• Replace or delete detected text: the original text is removed and the background behind it is rebuilt deterministically (texture- and grain-preserving reconstruction; no AI)
• Font size estimated from the detected text; add new text; markup and signatures; crop, rotate, flip
• Undo/redo, saved edits, export to Photos (PNG/JPEG) at full resolution, Share

App

• Library with search, filters, sort, grid/list views, rename, duplicate, share, delete
• Light/dark mode, iOS-style interface, haptics
• Works fully offline; the Android release build has no INTERNET permission

Technology

Project layout

src/
  features/pdf        PDF editor model, selection, verification, rendering cache
  features/image      Image editing, render plan, background reconstruction
  features/ocr        OCR normalization and font size estimation
  screens/            Library, PDF editor, image editor, settings
  ui/                 Shared iOS-style controls, theme, overlays
android/app/src/main/cpp/pdfium   PDFium C++ engine (shared with iOS)
android/app/src/main/java/...     Kotlin native modules (PDF, image, OCR, storage)
ios/PieNative                     iOS native modules and C ports
__tests__/                        Jest suites (1,026 tests)
scripts/                          iOS PDFium fetch script, reconstruction parity check

Building

Requirements: Node.js 22.11+, JDK 17 (Android Studio's JBR works), Android SDK with NDK 27.1.12297006. iOS builds need a Mac with Xcode and CocoaPods.

npm install
npm run typecheck
npm test

Android

cd android
./gradlew assembleRelease     # APK: android/app/build/outputs/apk/release/app-release.apk
./gradlew bundleRelease       # AAB: android/app/build/outputs/bundle/release/app-release.aab

Release signing reads android/keystore.properties and the upload keystore, which are not committed. Without them, use ./gradlew assembleDebug for a debug build, or npm run android with Metro running (npm start).

iOS

./scripts/fetch-pdfium-ios.sh   # downloads the PDFium xcframework into ios/PieNative/Vendor
cd ios && pod install && cd ..
npm run ios

Testing

• npm test: 58 Jest suites, 1,026 tests (editing models, PDF verification, OCR, reconstruction, persistence, UI behaviour)
• npm run typecheck: TypeScript strict
• scripts/inpainting-parity/run-parity.sh: checks that the Kotlin and C reconstruction ports are byte-identical to the TypeScript reference

The Android release build has been installed and checked on a physical device (OnePlus, Android 16): PDF creation from photos, merge, add image, text selection/edit/delete, save/reopen, OCR, text replace/delete with reconstruction, export, and restart.

Privacy

All documents stay in the app's private storage on the device. PIE has no account, no analytics, no cloud storage and no network access in the Android release build.

Built With

• c
• c++
• cmake
• javascript
• kotlin
• objective-c
• objective-c++
• python
• ruby
• shell
• swift
• typescript