Merge PDF Feature API & SDK

Combine Multiple PDFs Programmatically

Transform Document Workflows with
Powerful PDF Merging

The Merge PDFs API and SDK provides developers with robust capabilities to combine multiple PDF files into a single document programmatically. This solution eliminates the complexity of PDF manipulation by offering a straightforward implementation path while maintaining complete document integrity.

Built for development teams that demand reliability and performance, our PDF merging technology works across platforms and integration models. Whether you're building desktop applications, web services, or automated workflows, you can implement professional-grade PDF merging with minimal code footprint and resource consumption.

Unlike generic document libraries that treat PDF as just another format, our purpose-built solution addresses the specific challenges of PDF merging: maintaining bookmarks, preserving form fields, handling password-protected documents, and ensuring pixel-perfect rendering in the combined output.

Core Technical Features

Flexible Page Selection & Ordering

Our PDF Merge API provides granular control over which pages to include in your final document. Specify individual pages, page ranges using dash notation (e.g., "3-7"), or comma-separated selections from each source document. Pages can be specified in any order during the request but will appear in ascending order in the processed document.

POST/pdf-merge/v1
  items[0].file
  items[0].password
  items[0].pages
  ...

This precision allows you to extract and combine only the relevant content from larger documents, reducing file size and improving document relevance for your users.

Password-Protected Document Support

Security shouldn't be a barrier to document processing. The Merge PDF API handles password-protected source documents through a simple parameter in your request. Each source file can have its own password, enabling workflows that combine documents with different security settings.

items[0].password
string
The password to open the file

This feature eliminates a common bottleneck in document automation pipelines where protected files typically require manual intervention.

Asynchronous Processing Architecture

Built for reliability at scale, our API implements an asynchronous processing model that returns an operation ID immediately while processing continues in the background:

{
  "id":"3fa85f64-5717-4562-b3fc-2c963f66afa6"
 }
  Check operation status using:

GET/operation/v1/{operationId}/status

This approach prevents timeouts on large documents and enables your application to handle multiple merge operations concurrently without blocking user interactions.

Multipart Request Handling

The API accepts multipart/form-data requests, making it straightforward to upload multiple PDF files in a single call. This implementation reduces network overhead and simplifies client-side code compared to APIs that require separate upload and processing steps.

multipart/form-data
Max size of all files is 10MB.

Each file in the request can include its own set of parameters, providing maximum flexibility for complex document assembly scenarios.

Batch Import Capabilities

Process multiple files in a single operation with our batch import functionality. There's no artificial limit on the number of files you can combine (subject only to the 10MB total size limitation per request). This capability is essential for scenarios like:
Combining monthly reports into quarterly summaries
Merging transaction receipts into statement documents
Assembling chapters into complete manuals or publications

The batch processing engine maintains consistent performance regardless of the number of input files, with predictable memory usage that scales linearly with document complexity.

Cross-Platform Implementation Options

Choose the implementation approach that fits your technology stack:

  • REST API

    Ideal for web applications and cloud-based workflows

  • SDK

    Perfect for desktop applications and offline processing scenarios

Both options provide identical merging capabilities with consistent output quality, ensuring your document processing works reliably across deployment models without compromising on features.

Technical Implementation

API Endpoint Overview

The primary endpoint for PDF merging operations is:

POST/pdf-merge/v1

This endpoint accepts a multipart form request containing the files to merge and their associated parameters.

Request Structure

Each file in the request includes three potential parameters:

File (required)

The binary PDF file data

Password (optional)

Password to open protected documents

Pages (optional)

Specific pages to include from this document

Files are processed in the order specified in the request (items[0], items[1], etc.), allowing you to control the sequence of content in the final document.

Response Handling

The API returns a 202 Accepted response with an operation ID when processing begins:

{
"id":"3fa85f64-5717-4562-b3fc-2c963f66afa6"
}

Your application should store this ID and poll the operations endpoint to determine when processing is complete:

GET/operation/v1/{operationId}/status

When the operation completes successfully, you'll receive a download URL for the merged document.

Error Handling

The API provides specific error codes to help diagnose issues:

  • 400

    Invalid request (malformed parameters, unsupported file types)

  • 401

    Unauthorized access (authentication issues)

Proper error handling in your implementation should account for these responses and provide appropriate feedback to users.

Implementation Advantages

Online Integration Flexibility

The REST API offers several advantages for web-based implementations:

Serverless Compatible: Deploy in serverless environments without PDF library dependencies

Cross-Browser Support: Process documents from any device or browser

Cloud Storage Integration: Accept files directly from services like Google Drive or Dropbox

No Client-Side Processing: Offload CPU-intensive operations to the API service

These capabilities make the API ideal for SaaS applications, web portals, and document management systems where client resources may be limited.

Offline Processing Power

The SDK implementation provides critical capabilities for desktop and server applications:

Zero Internet Dependency: Process documents without network connectivity

Local Resource Utilization: Use available system resources for faster processing

Data Privacy: Keep sensitive documents within your network boundary

Integration with Local Storage: Work directly with file system documents

This approach is particularly valuable for regulated industries where data must remain within controlled environments, or for applications that need to function in disconnected scenarios.

Document Quality Preservation

Unlike generic tools that can lose formatting during combination, our merge technology preserves:

  • Original page dimensions and orientation
  • Text searchability and selection
  • Document metadata and properties
  • Vector graphics quality
  • Form fields and interactivity
  • Bookmarks and internal links

The result is a professional-grade document that maintains all the functionality of the source files while presenting a unified reading experience.

Why Choose Our PDF Merge Solution?

Developer-First Design

Our API and SDK are built by developers for developers, with:

Clean, consistent interfaces that follow REST principles

Predictable behavior across different document types

Comprehensive error reporting for faster debugging

Minimal dependencies to reduce integration complexity

This approach reduces implementation time and maintenance overhead compared to general-purpose document libraries.

Production-Ready Performance

Built for business-critical applications with demanding requirements:

Consistent memory usage even with large documents

Predictable processing times for operation planning

Thread-safe implementation for concurrent processing

Graceful handling of malformed or corrupted PDFs

These characteristics make our solution suitable for both high-volume batch processing and interactive user-facing applications.

Complete Control Over Document Workflows

Unlike cloud-only solutions, our dual implementation options give you:

  • Freedom to choose between API and SDK based on project requirements
  • Ability to implement hybrid approaches (online/offline processing)
  • Direct ownership of the document processing pipeline
  • Customization options not available with generic tools

This flexibility ensures your document workflows can adapt to changing business requirements without architectural rework.

Frequently Asked Questions

Will the quality of my PDF files be affected after merging them?

No. Our merging technology maintains 100% of the original document quality, including text sharpness, image resolution, and color accuracy. Vector graphics remain crisp regardless of viewing zoom level.

How can I merge PDFs offline?

The Avanquest PDF SDK enables complete offline PDF merging capabilities. Implement the SDK in your application to process documents locally without internet connectivity, while maintaining all the advanced features available in the API version.

How can I access my PDF once it is merged?

With the API implementation, you'll receive a download URL when processing completes. Your application can either download the file automatically or present the link to users. With the SDK implementation, you can save the merged document directly to any accessible file location.

What are the file size limitations?

The API accepts up to 10MB total file size per request. For larger documents, consider breaking the merge operation into multiple requests or implementing the SDK for local processing without size restrictions.

Can I merge specific pages rather than entire documents?

Yes. Both the API and SDK support granular page selection through the pages parameter. Specify individual pages or page ranges (e.g., "1,3,5-7") to extract and combine only the content you need from each source document.

Get Started With PDF Merge

Immediate Implementation

Register for API Access: Create a developer account to receive your API key

Review Documentation: Access our comprehensive API reference

Make Your First Request: Use the code samples to implement basic merging

Explore Advanced Features: Add page selection and document security handling

Developer Resources

API Reference: Complete endpoint documentation

SDK Downloads: Platform-specific implementation packages

Code Samples: Working examples in multiple languages

Integration Guides: Step-by-step implementation tutorials

Start building powerful document workflows with our PDF Merge API and SDK today.