ComPDF SDK for Flutter

As part of the KDAN ecosystem, ComPDF SDK for Flutter helps developers integrate PDF viewing, annotation, editing, form, and signing capabilities into cross-platform mobile apps.

It provides a production-ready Flutter wrapper around native ComPDF SDK capabilities for both Android and iOS projects.

If you find ComPDF SDK useful, please consider giving us a ⭐ Star on GitHub — it helps us grow and improve! Got questions or ideas? Join the conversation in our Discussions.

Why ComPDF SDK for Flutter?

• Easy to Integrate: Integrate PDF functionalities easily with our powerful SDK and clear documentation and guides with few lines of code.

• Fully Customizable UI: Design a unique interface for your products with fully customizable UI source code by a high-performing SDK.

• Comprehensive PDF Features: Supports generation, viewing, annotation, page editing, content editing, conversion, OCR, redaction, signing, forms, parsing, measurement, compression, comparison, color separation, batch processing, and more.

• Faster Time-to-Market: Comprehensive SDK libraries save your time and expenses and roll out your applications and projects.

• High-quality Service: We provide 24/7 professional one-to-one technical support, including onsite service and remote assistance via phone and email.

Table of Contents

• Supported Features
• Requirements
• How to Build the Flutter PDF Editor
• Apply the License Key
• Run Project
• Example App
• Free Trial & License
• Support
• Changelog
• Related

Supported Features

Viewer: Fast and smooth PDF rendering and viewing

• Display Modes - single/double page, vertical & horizontal scrolling, cover mode, crop mode
• Text Search & Selection
• PDF Navigation - outlines, bookmarks

Annotations:

• Notes - add longer comments with adjustable icon shape and color

• Ink - freehand drawing with customizable color, opacity, line thickness

• Text - add, move, resize text directly on page

• Inspector - adjust annotation looks (line styles, borders, colors, opacity, font)

• Comment on Annotations and Update Status

• Import & Export & Flatten Annotations (XFDF, FDF, JSON)

• Highlight, Underline, Strikeout, Squiggly

• Shapes - Rectangle, Oval, Line, Arrow, Polygon, Polyline, Cloud

• Stamps, Sound, Movie, File Attachment, Link, Distance, Perimeter, Area

Forms:

• Process fillable and static PDF forms

• Form filling, form creation, form flattening

Document Editor:

• Page manipulation - insert, delete, rotate, reorder, extract, crop

• Split PDF, Merge PDF

Content Editor: Edit PDF text and images directly like in Word

Security:

• Encryption - set open password, permission password

• Restrict printing, copying, editing

Signatures:

• Electronic Signatures - draw, type, image signatures

• Digital Signatures - certificate-based signature validation

Watermark:

• Add Text or Image Watermarks

• Delete Watermarks

• Customize Watermarks

OCR:

• AI OCR

• Recognize Tables, Graphics, Images

• Support recognition in 80+ Languages

Compare Documents: Side-by-side document comparison to highlight differences

Redaction: Permanently remove sensitive content from PDFs

Measurement: Distance, area, perimeter measurement tools

Compress: Optimize and reduce PDF file size

Convert Files:

• Convert PDF to Word, Excel, PPT, HTML, CSV, images (PNG,JPEG, JPEG, JPEG2000, BMP, TIFF, TGA, GIF), RTF, TXT, JSON, XML, markdown, searchable PDF, searchable OFD.

• Convert images (PNG,JPEG, JPEG, JPEG2000, BMP, TIFF, TGA, GIF) to Word, Excel, PPT, HTML, CSV, RTF, TXT, JSON, XML.

• Convert Word, Excel, PPT, HTML, CSV, PNG, RTF, TXT to PDF

UI Customization:

• Toolbar Customization

• UI Personalization

• Ready-Made UI Options

• Out-of-the-box Source Code

Requirements

Before starting, please make sure that you have already met the following prerequisites:

Get ComPDF License Key

ComPDF offers two types of license keys: a free 30-day trial license and a commercial license.

• Trial License – You can request a 30-day free trial online.
• Commercial License – For advanced features, custom requirements, or quote inquiries, feel free to contact our sales.

For the Flutter PDF SDK, the commercial license must be bound to your application’s ApplicationId and iOS BundleId.

System Requirements

Android

Please install the following required packages:

• The latest stable version of Flutter
• The latest stable version of Android Studio
• The Android NDK
• An Android Virtual Device

Operating Environment Requirements:

• A minSdkVersion of 21 or higher.
• A compileSdkVersion of 34 or higher.
• A targetSdkVersion of 34 or higher.
• Android ABI(s): x86, x86_64, armeabi-v7a, arm64-v8a.

iOS

Please install the following required packages:

• The latest stable version of Flutter
• The latest stable version of Xcode
• The latest stable version of CocoaPods. Follow the CocoaPods installation guide to install it.

Operating Environment Requirements:

• The iOS 12.0 or higher.
• The Xcode 12.0 or newer for Objective-C or Swift.

How to Build the Flutter PDF Editor

Create a new project

Android

1. Create a Flutter project called example with the flutter CLI:

flutter create --org com.compdfkit.flutter example

2. In the terminal app, change the location of the current working directory to your project:

cd example

3. open example/android/app/src/main/AndroidManifest.xml , add Internet Permission and Storage Permission:

<manifest xmlns:android="http://schemas.android.com/apk/res/android"
    package="com.compdfkit.flutter.example">

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

    <!-- Required to read and write documents from device storage -->
+    <uses-permission android:name="android.permission.READ_EXTERNAL_STORAGE"/>
+    <uses-permission android:name="android.permission.WRITE_EXTERNAL_STORAGE"/>

    <!-- Optional settings -->
+    <uses-permission android:name="android.permission.MANAGE_EXTERNAL_STORAGE"/>


    <application
+      android:requestLegacyExternalStorage="true">

    </application>   
</manifest>

4. Open the app's Gradle build file, android/app/build.gradle:

open android/app/build.gradle

5. Modify the minimum SDK version, All this is done inside the android section:

 android {
     defaultConfig {
-        minSdkVersion flutter.minSdkVersion
+        minSdkVersion 21
         ...
     }
 }

6. Open the project’s main activity class, android/app/src/main/java/com/example/compdfkit/flutter/example/MainActivity.java, Change the base Activity to extend FlutterFragmentActivity:

- import io.flutter.embedding.android.FlutterActivity;
+ import io.flutter.embedding.android.FlutterFragmentActivity;

- public class MainActivity extends FlutterActivity {
+ public class MainActivity extends FlutterFragmentActivity {
}

Alternatively you can update the AndroidManifest.xml file to use FlutterFragmentActivity as the launcher activity:

<activity
-     android:name=".MainActivity" 
+     android:name="io.flutter.embedding.android.FlutterFragmentActivity"
      android:exported="true"
      android:hardwareAccelerated="true"
      android:launchMode="singleTop"
      android:theme="@style/LaunchTheme"
      android:windowSoftInputMode="adjustPan">

Note: FlutterFragmentActivity is not an official part of the Flutter SDK. If you need to use CPDFReaderWidget in ComPDF for Flutter, you need to use this part of the code. You can skip this step if you don't need to use.

7. Add the ComPDF dependency in pubspec.yaml

 dependencies:
   flutter:
     sdk: flutter
+  compdfkit_flutter: ^2.6.9

8. Add the PDF documents you want to display in the project

• create a pdf directory

  mkdir pdfs
  

• Copy your example document into the newly created pdfs directory and name it PDF_Document.pdf

9. Specify the assets directory in pubspec.yaml

 flutter:
+  assets:
+    - pdfs/

10. From the terminal app, run the following command to get all the packages:

flutter pub get

iOS

1. Create a Flutter project called example with the flutter CLI:

flutter create --org com.compdfkit.flutter example

2. In the terminal app, change the location of the current working directory to your project:

cd example

3. Add the ComPDF dependency in pubspec.yaml

 dependencies:
   flutter:
     sdk: flutter
+  compdfkit_flutter: ^2.6.9

4. Open your project's Podfile in a text editor:

open ios/Podfile

Note: If SSL network requests fail to download the ComPDFKit library when you run pod install, you can see the processing method in Troubleshooting).

6. Update the platform to iOS 12 and add the ComPDF Podspec:

- platform :ios, '9.0'
+ platform :ios, '12.0' 
 ...
 target 'Runner' do
   use_frameworks!
   use_modular_headers!`

   flutter_install_all_ios_pods File.dirname(File.realpath(__FILE__))
+  pod 'ComPDFKit', :git => 'https://github.com/ComPDFKit/compdfkit-pdf-sdk-ios-swift.git', :tag => '2.6.9'
+  pod 'ComPDFKit_Tools', :git => 'https://github.com/ComPDFKit/compdfkit-pdf-sdk-ios-swift.git', :tag => '2.6.9'
 end

7. Go to the example/ios folder and run the pod install command:

pod install

8. Add the PDF documents you want to display in the project

• create a pdf directory

  mkdir pdfs
  

• Copy your example document into the newly created pdfs directory and name it PDF_Document.pdf

9. Specify the assets directory in pubspec.yaml

 flutter:
+  assets:
+    - pdfs/

10. To protect user privacy, before accessing the sensitive privacy data, you need to find the "*Info*" configuration in your iOS 10.0 or higher iOS project and configure the relevant privacy terms as shown in the following picture.

<key>NSCameraUsageDescription</key>
<string>Your consent is required before you could access the function.</string>

<key>NSMicrophoneUsageDescription</key>
<string>Your consent is required before you could access the function.</string>

<key>NSPhotoLibraryAddUsageDescription</key>
<string>Your consent is required before you c