flutter_pdf_annotations

A Flutter plugin for opening and annotating PDF files natively on iOS and Android.

Presents a full-screen native editor with freehand drawing, highlighting, image stamping, erasing, undo, color picker, and pen-size presets — then saves the annotated PDF back to a file path of your choice.

Features

Feature	Description
Freehand pen	Draw with custom colour and stroke width
Highlighter	Semi-transparent highlight with adjustable opacity
Image stamps	Place signatures, logos, or images — resize, accept, or delete
Eraser	Remove individual annotations
Undo	Step back through all annotation types
Save	Write the annotated PDF to any writable path
Share	Share via the native share sheet
Multiple sources	Open from file path, raw bytes, URL, or Flutter asset
Typed results	Distinguish success, cancellation, and errors without try/catch

Platform Support

Android	iOS
API 21+	iOS 14+

Getting Started

1. Install

dependencies:
  flutter_pdf_annotations: ^1.1.0

flutter pub get

2. Platform Setup

Android

No extra permissions or setup needed for paths inside the app's own directories (getExternalFilesDir, filesDir).

If you plan to download PDFs from the internet using openFromUrl, make sure your AndroidManifest.xml includes:

<uses-permission android:name="android.permission.INTERNET"/>

iOS

If you allow the user to pick images for stamping, add to ios/Runner/Info.plist:

<key>NSPhotoLibraryUsageDescription</key>
<string>Select images to insert into PDF annotations</string>

Usage

Open a local PDF

import 'package:flutter_pdf_annotations/flutter_pdf_annotations.dart';

final result = await FlutterPdfAnnotations.openPDF(
  filePath: '/path/to/document.pdf',
);

if (result.isSuccess) {
  print('Saved to: ${result.savedPath}');
} else if (result.isCancelled) {
  print('User cancelled');
} else {
  print('Error: ${result.error}');
}

With configuration

final result = await FlutterPdfAnnotations.openPDF(
  filePath: '/path/to/document.pdf',
  savePath: '/path/to/annotated.pdf',
  config: PDFAnnotationConfig(
    title: 'Review Contract',
    initialPenColor: Colors.red,
    initialHighlightColor: Colors.yellow.withOpacity(0.5),
    initialStrokeWidth: 3.0,
  ),
);

With image stamps

final signatureBytes = await File('signature.png').readAsBytes();

final result = await FlutterPdfAnnotations.openPDF(
  filePath: '/path/to/document.pdf',
  config: PDFAnnotationConfig(
    title: 'Sign Document',
    imagesToInsert: [signatureBytes],
  ),
);

From raw bytes

final Uint8List pdfBytes = /* from network, database, etc. */;

final result = await FlutterPdfAnnotations.openFromBytes(
  bytes: pdfBytes,
  config: PDFAnnotationConfig(title: 'In-Memory PDF'),
);

From a URL

final result = await FlutterPdfAnnotations.openFromUrl(
  url: 'https://example.com/document.pdf',
  config: PDFAnnotationConfig(title: 'Remote PDF'),
);

From a Flutter asset

// Declare in pubspec.yaml:
//   flutter:
//     assets:
//       - assets/sample.pdf

final result = await FlutterPdfAnnotations.openFromAsset(
  assetPath: 'assets/sample.pdf',
);

API Reference