How to Add Barcode Signatures to PDF Documents in Java

Introduction

Ever needed to track who signed a document, when they signed it, or embed product information directly into a contract—all while keeping it machine-readable? You’re not alone. Traditional digital signatures work great for authentication, but they don’t always make it easy to embed and retrieve structured data.

That’s where barcode signatures come in handy. Instead of (or in addition to) a standard digital signature, you can embed a scannable barcode right into your PDF. Think of it like adding a QR code to your business card—except this one proves document authenticity while carrying important metadata that any barcode scanner can read.

In this guide, I’ll walk you through adding barcode signatures to PDFs using GroupDocs.Signature for Java. We’ll specifically use GS1 Composite Barcodes (the kind you see on retail products), but the approach works for dozens of other barcode types too.

What you’ll learn:

• Why barcode signatures matter for document tracking and compliance
• How to set up GroupDocs.Signature in your Java project
• Step-by-step code for adding GS1CompositeBar barcodes to PDFs
• Positioning, styling, and customization options
• Common pitfalls and how to avoid them
• Real-world scenarios where this technique shines

Let’s dive in.

Why Use Barcode Signatures?

Before we jump into code, let’s talk about why you’d want to use barcode signatures instead of (or alongside) traditional digital signatures.

Traditional digital signatures are excellent for proving a document hasn’t been tampered with and verifying who signed it. But they’re not great for:

• Quick visual verification without special software
• Embedding structured data that external systems can scan
• Integrating with warehouse or inventory management systems
• Creating audit trails that work with existing barcode infrastructure

Barcode signatures solve these problems by making your signature machine-readable. Here’s what that means in practice:

• Supply chain documents: Add a barcode to your shipping manifests that contains order numbers, destination codes, and tracking IDs. Warehouse staff can scan it instantly without opening the PDF.
• Healthcare records: Embed patient IDs and document reference numbers directly into consent forms. Medical record systems can scan and file them automatically.
• Financial contracts: Include transaction IDs and compliance codes that auditing software can extract and verify programmatically.
• Quality control: Sign inspection reports with barcodes containing batch numbers and inspector credentials for instant traceability.

The best part? You’re not choosing between security and convenience. GroupDocs.Signature lets you add both traditional digital signatures AND barcode signatures to the same document.

Prerequisites

Before we start coding, make sure you’ve got these basics covered:

Required Setup

Java Development Kit: You’ll need JDK 8 or later. If you’re on a newer version (11, 17, or 21), even better—everything works smoothly.

Build Tool: Maven or Gradle for dependency management. I’ll show you both approaches, so use whichever you prefer.

IDE: Any Java IDE works fine. IntelliJ IDEA, Eclipse, and VS Code are all popular choices.

Adding GroupDocs.Signature to Your Project

This is the library that does all the heavy lifting. It handles dozens of barcode types, multiple document formats, and makes the whole process surprisingly straightforward.

For Maven users, add this to your pom.xml:

<dependency>
    <groupId>com.groupdocs</groupId>
    <artifactId>groupdocs-signature</artifactId>
    <version>23.12</version>
</dependency>

For Gradle users, add this to your build.gradle:

implementation 'com.groupdocs:groupdocs-signature:23.12'

About licensing: GroupDocs offers a free trial that’s perfect for testing and development. You can download it from their releases page. When you’re ready for production, you’ll need to purchase a license or request a temporary one from the GroupDocs website.

Knowledge Requirements

You don’t need to be a Java expert, but you should be comfortable with:

• Basic object-oriented programming concepts
• File path handling in Java
• Try-catch blocks for error handling (we’ll use these for proper resource management)

If you’ve worked with any document processing libraries before, you’ll feel right at home. If not, don’t worry—I’ll explain everything as we go.

Setting Up Your Environment

Let’s get your development environment ready. This part’s pretty quick if you’ve already added the dependency above.

Basic Initialization

First, you need to create a Signature object—this is your main entry point for all document signing operations. Here’s the simplest possible example:

import com.groupdocs.signature.Signature;

// Point to your PDF file
Signature signature = new Signature("path/to/your/document.pdf");

Important note about resource management: The Signature object holds file handles and memory resources, so you should always dispose of it when you’re done. The recommended approach is using a try-finally block (or try-with-resources if you prefer). We’ll see this in action in the next section.

Step-by-Step Implementation

Now for the fun part—let’s actually sign a PDF with a barcode. I’ll break this down into digestible steps so you can follow along easily.

Step 1: Set Up Your File Paths

First things first: you need to tell the code where to find your PDF and where to save the signed version.

String filePath = "YOUR_DOCUMENT_DIRECTORY" + "/sample.pdf";
String fileName = new java.io.File(filePath).getName();
String outputPath = "YOUR_OUTPUT_DIRECTORY" + "/SignedWithBarcodeGS1CompositeBar/" + fileName;

Pro tip: Use environment variables or configuration files for these directory paths instead of hardcoding them. It makes your code much more portable. For example:

String documentDir = System.getenv("DOCUMENT_DIR");
String outputDir = System.getenv("OUTPUT_DIR");

Step 2: Initialize the Signature Object

Next, create your Signature object with proper resource management:

Signature signature = new Signature(filePath);

This opens your PDF and prepares it for signing. The library loads the document into memory and analyzes its structure so it knows where signatures can be placed.

Step 3: Configure Your Barcode

Here’s where things get interesting. You’re going to create a BarcodeSignOptions object that defines everything about your barcode: what data it contains, what type it is, and where it appears on the page.

import com.groupdocs.signature.options.sign.BarcodeSignOptions;
import com.groupdocs.signature.domain.barcodes.BarcodeTypes;

// Create barcode with GS1 format data
BarcodeSignOptions options = new BarcodeSignOptions("(01)03212345678906/(21)A1B2C3D4E5F6G7H8");
options.setEncodeType(BarcodeTypes.GS1CompositeBar);

What’s happening here? The string "(01)03212345678906/(21)A1B2C3D4E5F6G7H8" follows the GS1 standard format:

• (01) indicates a GTIN (Global Trade Item Number)
• 03212345678906 is the actual product identifier
• (21) indicates a serial number
• A1B2C3D4E5F6G7H8 is the unique serial number

If you’re working with supply chain documents, you’ll recognize this format. If not, don’t worry—you can encode any string you want. The GS1 format just happens to be industry-standard for product tracking.

Other barcode types you can use:

• BarcodeTypes.QR for QR codes (great for URLs or large text)
• BarcodeTypes.Code128 for alphanumeric data
• BarcodeTypes.DataMatrix for compact 2D codes
• BarcodeTypes.PDF417 for driver’s licenses and ID cards

There are over 60 supported types—check the GroupDocs documentation for the full list.

Step 4: Position and Customize

Now let’s decide where this barcode appears on your PDF and how it looks:

// Set position and apply to all pages
options.setTop(200); // Set vertical position
options.setAllPages(true);

Positioning explained:

• setTop(200) places the barcode 200 pixels from the top of the page
• setAllPages(true) adds the barcode to every page in the document

You can get much fancier with positioning:

options.setLeft(100);        // 100 pixels from left edge
options.setTop(200);         // 200 pixels from top
options.setWidth(300);       // Barcode width in pixels
options.setHeight(100);      // Barcode height in pixels
options.setPageNumber(1);    // Only sign page 1 (removes setAllPages)

Visual customization options:

options.setMargin(new Padding(10));           // Add padding around barcode
options.setBackground(new Background());       // Set background color
options.setForeColor(Color.BLACK);            // Barcode color
options.setBackgroundColor(Color.WHITE);      // Background color

Step 5: Sign the Document

Finally, let’s actually apply the signature and save the result:

try {
    SignResult signResult = signature.sign(outputPath, options);
    System.out.println("Document signed successfully!");
    System.out.println("Signed document saved to: " + outputPath);
} finally {
    if (signature != null) {
        signature.dispose();
    }
}

Why the try-finally block? This ensures that even if something goes wrong during signing (file locked, disk full, invalid barcode data), the Signature object still gets disposed properly. This releases file handles and frees up memory.

What’s in the SignResult? The signResult object contains useful info:

• Number of signatures applied
• Whether signing succeeded
• Any warnings or errors encountered

You can check these values to confirm everything worked:

if (signResult.getSucceeded().size() > 0) {
    System.out.println("Successfully added " + signResult.getSucceeded().size() + " signature(s)");
}

Complete Working Example

Here’s everything put together in one clean method:

import com.groupdocs.signature.Signature;
import com.groupdocs.signature.options.sign.BarcodeSignOptions;
import com.groupdocs.signature.domain.barcodes.BarcodeTypes;

public class BarcodeSigningExample {
    
    public void signPdfWithBarcode(String inputPath, String outputPath) {
        Signature signature = null;
        
        try {
            // Initialize signature
            signature = new Signature(inputPath);
            
            // Configure barcode
            BarcodeSignOptions options = new BarcodeSignOptions(
                "(01)03212345678906/(21)A1B2C3D4E5F6G7H8"
            );
            options.setEncodeType(BarcodeTypes.GS1CompositeBar);
            options.setTop(200);
            options.setAllPages(true);
            
            // Sign and save
            SignResult result = signature.sign(outputPath, options);
            
            System.out.println("Signing completed: " + result.getSucceeded().size() + " signature(s) added");
            
        } catch (Exception e) {
            System.err.println("Error signing document: " + e.getMessage());
            e.printStackTrace();
        } finally {
            if (signature != null) {
                signature.dispose();
            }
        }
    }
}

This method is production-ready. It handles errors gracefully, cleans up resources properly, and provides feedback about what happened.

Working with Different Barcode Types

The beauty of GroupDocs.Signature is its flexibility. While we’ve focused on GS1CompositeBar barcodes, you can easily switch to other types depending on your needs.

Choosing the Right Barcode Type

Here’s a quick guide to help you decide:

For product tracking and supply chain:

• GS1CompositeBar - Industry standard for retail and logistics
• GS1Code128 - Simpler version for basic product IDs

For document management:

• QR - Perfect for embedding URLs or large amounts of text
• PDF417 - Used in government IDs and airline boarding passes

For compact data storage:

• DataMatrix - Great for small labels (think electronics components)
• Aztec - Similar to DataMatrix, used in transportation

For simple numeric codes:

• Code39 - Alphanumeric, easy to print
• Code128 - More compact than Code39

Switching Barcode Types

Changing the barcode type is literally one line of code:

// Define barcode sign options with sample text
BarcodeSignOptions options = new BarcodeSignOptions("Sample Text");

// Assign specific barcode type
options.setEncodeType(BarcodeTypes.GS1CompositeBar);

Just swap out BarcodeTypes.GS1CompositeBar for any other type:

options.setEncodeType(BarcodeTypes.QR);           // QR code
options.setEncodeType(BarcodeTypes.Code128);      // Code 128
options.setEncodeType(BarcodeTypes.DataMatrix);   // Data Matrix

Important: Different barcode types have different data capacity limits. For example:

• Code39 is limited to alphanumeric characters
• QR codes can hold thousands of characters
• GS1 barcodes require specific formatting (the parentheses notation we saw earlier)

Always check your barcode type’s specifications before encoding large amounts of data.

Real-World Use Cases

Let’s look at some practical scenarios where barcode signatures really shine:

Supply Chain Management

Scenario: You’re signing shipping manifests that warehouse staff need to process quickly.

Implementation:

BarcodeSignOptions options = new BarcodeSignOptions(
    "(01)" + gtin + "/(21)" + serialNumber + "/(10)" + batchNumber
);
options.setEncodeType(BarcodeTypes.GS1CompositeBar);

Benefit: Staff can scan the barcode on the signed manifest and instantly pull up order details, inventory data, and shipping routes without opening the PDF manually.

Healthcare Documentation

Scenario: Patient consent forms need to be filed in an electronic medical records system.

Implementation:

String patientData = "PATIENT_ID:" + patientId + "|DOC_TYPE:CONSENT|DATE:" + dateString;
BarcodeSignOptions options = new BarcodeSignOptions(patientData);
options.setEncodeType(BarcodeTypes.QR);

Benefit: Medical staff can scan the QR code and the document automatically routes to the correct patient record with proper categorization.

Financial Services

Scenario: Loan agreements need embedded transaction IDs for compliance auditing.

Implementation:

String complianceData = "TXN:" + transactionId + "|AGENT:" + agentId + "|BRANCH:" + branchCode;
BarcodeSignOptions options = new BarcodeSignOptions(complianceData);
options.setEncodeType(BarcodeTypes.PDF417);

Benefit: Auditors can scan documents to instantly verify transaction details against database records without manual data entry.

Manufacturing Quality Control

Scenario: Inspection reports need to link back to specific production batches.

Implementation:

String qcData = "BATCH:" + batchNumber + "|INSPECTOR:" + inspectorId + "|RESULT:" + passFailStatus;
BarcodeSignOptions options = new BarcodeSignOptions(qcData);
options.setEncodeType(BarcodeTypes.DataMatrix);

Benefit: If a quality issue arises, you can quickly scan inspection reports to trace which inspector approved which batch, enabling rapid root cause analysis.

Common Implementation Issues

Even with straightforward code, you’ll probably run into a few hiccups. Here are the most common problems I’ve seen and how to fix them:

Issue 1: “File is already in use” Exception

Symptom: You get an IOException saying the file can’t be accessed.

Cause: You didn’t dispose the Signature object from a previous operation, so the file handle is still locked.

Fix: Always use try-finally blocks:

Signature signature = null;
try {
    signature = new Signature(filePath);
    // ... your code ...
} finally {
    if (signature != null) {
        signature.dispose();
    }
}

Issue 2: Barcode Doesn’t Appear on PDF

Symptom: The signing completes without errors, but no barcode is visible.

Possible causes:

1. Positioning is off-page: Your setTop() or setLeft() values are larger than the page dimensions
2. Barcode is too small: Try increasing width and height
3. Colors match background: White barcode on white page won’t show

Fix:

// Make sure dimensions are reasonable
options.setTop(100);      // Not 10000
options.setLeft(100);
options.setWidth(300);    // At least 200 pixels for readability
options.setHeight(100);

// Ensure contrast
options.setForeColor(Color.BLACK);
options.setBackgroundColor(Color.WHITE);

Issue 3: “Invalid Barcode Data” Exception

Symptom: Exception thrown when calling sign().

Cause: Your data string doesn’t match the barcode type’s requirements. GS1 barcodes especially have strict formatting rules.

Fix for GS1 barcodes: Always use application identifiers in parentheses:

// Correct:
"(01)03212345678906/(21)ABC123"

// Incorrect:
"03212345678906ABC123"

Fix for other types: Check the barcode specification. For example, Code39 doesn’t support lowercase letters.

Issue 4: OutOfMemoryError with Large PDFs

Symptom: JVM runs out of memory when processing large documents.

Cause: Loading huge PDFs into memory all at once.

Fix: Process documents in batches and increase JVM heap size:

java -Xmx2G -jar your-application.jar

Also, consider signing pages individually instead of using setAllPages(true) for massive documents.

Issue 5: Barcode Scanning Fails

Symptom: The barcode is visible but scanners can’t read it.

Possible causes:

1. Barcode is too small: Most scanners need at least 200x100 pixels
2. Low contrast: Gray barcode on light gray background
3. Compression artifacts: PDF compression mangled the barcode

Fix:

// Increase size
options.setWidth(400);
options.setHeight(150);

// Maximize contrast
options.setForeColor(Color.BLACK);
options.setBackgroundColor(Color.WHITE);

// Add quiet zone (blank space around barcode)
options.setMargin(new Padding(10));

Security and Validation

Adding a barcode to a document is one thing—ensuring it’s legitimate and hasn’t been tampered with is another. Let’s talk about security considerations.

Are Barcode Signatures Secure?

Short answer: By themselves, no. Barcodes are just encoded data—anyone with the right tool can generate them.

Complete answer: When combined with digital signatures, yes. Here’s the recommended approach:

1. Add digital signature first to cryptographically secure the document
2. Then add barcode signature for easy scanning and data embedding
3. Verify both when validating documents

Implementing Dual Signatures

Here’s how to add both a digital signature and a barcode signature:

// First, add digital signature
DigitalSignOptions digitalOptions = new DigitalSignOptions("certificate.pfx");
digitalOptions.setPassword("cert_password");
signature.sign(outputPath, digitalOptions);

// Then, add barcode on top
BarcodeSignOptions barcodeOptions = new BarcodeSignOptions("DATA");
barcodeOptions.setEncodeType(BarcodeTypes.QR);
signature.sign(outputPath, barcodeOptions);

This way, your document is:

• Legally binding (digital signature)
• Tamper-evident (digital signature)
• Machine-readable (barcode)
• Easily traceable (barcode data)

Validating Barcode Data

When you scan a barcode from a signed document, you should verify that:

1. The document’s digital signature is valid
2. The barcode data matches expected patterns
3. Referenced IDs exist in your database

Example validation logic:

public boolean validateScannedBarcode(String scannedData, String documentPath) {
    // Verify digital signature first
    if (!verifyDigitalSignature(documentPath)) {
        return false;
    }
    
    // Validate barcode format
    if (!scannedData.matches("(01)\\d{14}/(21)[A-Z0-9]+")) {
        return false;
    }
    
    // Check against database
    String productId = extractProductId(scannedData);
    return database.productExists(productId);
}

Performance Considerations

When you’re signing hundreds or thousands of documents, performance matters. Here are some optimization strategies:

Resource Management

Always dispose of Signature objects. This is crucial for preventing memory leaks:

signature.dispose();

If you’re processing multiple documents, dispose after each one:

for (String filePath : documentPaths) {
    Signature signature = null;
    try {
        signature = new Signature(filePath);
        // ... signing logic ...
    } finally {
        if (signature != null) {
            signature.dispose();
        }
    }
}

Batch Processing

When processing multiple documents, consider:

Sequential processing for smaller batches (< 100 documents):

for (String path : paths) {
    signDocument(path);
}

Parallel processing for larger batches:

paths.parallelStream().forEach(path -> signDocument(path));

Important: Be careful with parallel processing—GroupDocs.Signature handles files, so you need to ensure you’re not overwhelming your disk I/O. Start with 4-8 parallel threads and adjust based on your hardware.

Memory Usage

For large PDFs (> 50MB):

• Increase JVM heap: -Xmx4G
• Process pages individually instead of using setAllPages(true)
• Clear references to large objects after use

For many small PDFs:

• Use object pooling to reuse Signature instances where possible
• Implement a queue system to avoid processing thousands simultaneously
• Monitor memory usage and implement backpressure if needed

Caching

If you’re using the same barcode configuration repeatedly:

// Create once, reuse many times
private static BarcodeSignOptions createStandardBarcodeOptions(String data) {
    BarcodeSignOptions options = new BarcodeSignOptions(data);
    options.setEncodeType(BarcodeTypes.GS1CompositeBar);
    options.setTop(200);
    options.setAllPages(true);
    return options;
}

This avoids repeatedly configuring the same options and can speed up batch operations significantly.

Next Steps and Advanced Features

You’ve now got the fundamentals down. Here are some advanced features you might want to explore:

Multiple Signatures on One Document

You can add multiple barcodes (or other signature types) to a single document:

// Add QR code in top-left
BarcodeSignOptions qrOptions = new BarcodeSignOptions("https://example.com");
qrOptions.setEncodeType(BarcodeTypes.QR);
qrOptions.setTop(50);
qrOptions.setLeft(50);
signature.sign(outputPath, qrOptions);

// Add GS1 barcode in bottom-right
BarcodeSignOptions gs1Options = new BarcodeSignOptions("(01)03212345678906");
gs1Options.setEncodeType(BarcodeTypes.GS1CompositeBar);
gs1Options.setTop(700);
gs1Options.setLeft(400);
signature.sign(outputPath, gs1Options);

Dynamic Barcode Content

Generate barcode content based on document metadata:

// Extract data from PDF or database
String orderId = extractOrderIdFromPdf(filePath);
String timestamp = LocalDateTime.now().format(DateTimeFormatter.ISO_DATE_TIME);
String barcodeData = String.format("ORDER:%s|TIME:%s", orderId, timestamp);

BarcodeSignOptions options = new BarcodeSignOptions(barcodeData);

Integration with Existing Systems

With Spring Boot:

@Service
public class DocumentSigningService {
    public void signWithBarcode(MultipartFile file, String barcodeData) {
        // ... implementation ...
    }
}

With REST APIs:

@PostMapping("/sign-document")
public ResponseEntity<byte[]> signDocument(
    @RequestParam("file") MultipartFile file,
    @RequestParam("barcode") String barcodeData
) {
    // Sign document and return as byte array
}

Learning Resources

Official documentation: The GroupDocs documentation is comprehensive. Check out:

• API Reference
• Developer Guide

Community support:

• GroupDocs Forum
• Stack Overflow (tag: groupdocs)

Wrapping Up

You’ve learned how to add barcode signatures to PDFs using Java—a powerful technique for making documents both secure and machine-readable. Here’s a quick recap:

Key takeaways:

• Barcode signatures add machine-readable data to documents without sacrificing security
• GS1CompositeBar is ideal for supply chain and retail applications
• Always combine barcode signatures with digital signatures for maximum security
• Proper resource management (disposing Signature objects) prevents memory leaks
• Different barcode types suit different use cases—choose based on your data and industry

What to do next:

1. Try the code examples in your own project
2. Experiment with different barcode types to see which fits your needs
3. Explore combining multiple signature types on one document
4. Check out the GroupDocs documentation for advanced features

Got questions or run into issues? The GroupDocs community forum is a great resource, and the official documentation covers edge cases in detail.

Happy coding, and may your documents always be scannable!

FAQ

Q: What is a GS1CompositeBar barcode?
A: A GS1CompositeBar combines linear and 2D barcode components to store more data in a compact format. It’s widely used in retail and supply chain management because it can encode product identifiers (GTINs), serial numbers, batch codes, and expiration dates all in one scannable barcode. Think of it as the barcode version of a product label’s entire information panel.

Q: Can I use different barcode types besides GS1CompositeBar?
A: Absolutely! GroupDocs.Signature supports over 60 barcode types including QR codes, Code128, DataMatrix, PDF417, and Aztec. Just change the setEncodeType() parameter. For example, use BarcodeTypes.QR for QR codes or BarcodeTypes.Code128 for standard linear barcodes. Choose based on your data size and industry requirements.

Q: Do I need a license to use GroupDocs.Signature?
A: You can start with a free trial for development and testing. For production use, you’ll need to purchase a license. GroupDocs offers temporary licenses for evaluation and various licensing options for commercial use. Check their purchase page for details.

Q: Can barcode scanners read barcodes from signed PDFs?
A: Yes, but the barcode must be large enough and have sufficient contrast. I recommend at least 200x100 pixels for reliable scanning. Standard smartphone barcode scanning apps can read QR codes from PDFs displayed on screen. For printed documents, any barcode scanner that supports your chosen barcode type will work.

Q: How do I handle errors during the signing process?
A: Always wrap your signing code in try-catch blocks and use try-finally to ensure proper resource cleanup. Common exceptions include IOException (file access issues), InvalidOperationException (invalid barcode data), and OutOfMemoryError (large documents). Log exceptions with full stack traces to help with debugging, and always call signature.dispose() in the finally block to release file handles.

Q: Can I add both digital signatures and barcode signatures to the same document?
A: Yes, and this is actually the recommended approach! Add the digital signature first for cryptographic security, then add the barcode signature for machine readability. This gives you both legal validity and practical convenience. Just call signature.sign() twice with different options objects.

Q: How much data can I store in a barcode?
A: It depends on the barcode type. Code39 and Code128 handle dozens of characters. QR codes can store several thousand characters. GS1CompositeBar typically handles 50-100 characters. DataMatrix is efficient for compact spaces. If you need to store large amounts of data, consider using a QR code and encoding a URL that points to your full data instead.

Q: What happens if someone modifies the PDF after signing?
A: If you’ve added a digital signature, any modification will invalidate it—this is by design and protects document integrity. The barcode itself doesn’t provide tamper protection (anyone can generate a new barcode), which is why combining both signature types is important. Always verify the digital signature before trusting barcode data.

Q: Can I customize the appearance of the barcode?
A: Yes! You can control size (width/height), position (top/left), colors (foreground/background), margins, and even add text labels above or below the barcode. The BarcodeSignOptions class provides extensive customization options. Just remember that extreme styling might affect scannability—always test with actual scanners.

Q: Does this work with other document formats besides PDF?
A: GroupDocs.Signature supports dozens of formats including Word documents (DOCX), Excel spreadsheets (XLSX), PowerPoint presentations (PPTX), and various image formats. The code structure is nearly identical—just change your input file path. Check the GroupDocs documentation for the complete list of supported formats.

Q: How do I extract barcode data from an already-signed document?
A: GroupDocs.Signature provides a search() method that can detect and extract barcode data from documents. You’ll need to use BarcodeSearchOptions to specify which barcode types to look for, then iterate through the results. This is useful for validating documents or building automated processing pipelines.

Q: Are there any file size limitations?
A: The library itself doesn’t impose strict size limits, but practical limitations exist based on available memory. Documents over 50MB may require increasing JVM heap size. For very large documents (100MB+), consider processing pages individually or implementing streaming approaches. Memory management becomes critical when batch processing multiple large files.

Q: Can I sign documents stored in cloud storage (S3, Azure Blob, etc.)?
A: Yes, but you’ll need to download the file locally first, sign it, and then upload it back. GroupDocs.Signature works with local file paths, not cloud URLs directly. Most cloud SDKs make this straightforward—download to a temp directory, process, then upload. Remember to clean up temp files afterward to avoid disk space issues.