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ShowPro Merge PDF: The Best Free Adobe Acrobat Online Alternative

ShowPro Team

Expert tool tutorials · showprosoftware.com

Updated June 14, 2026

Why Seek a Free Adobe Acrobat Online Alternative for PDF Merging?

The quest for a reliable "free Adobe Acrobat online alternative" often stems from a direct experience with the limitations and inherent drawbacks of server-based PDF tools. While Adobe Acrobat Online provides basic PDF functionalities, its "free" offering comes with strings attached that can significantly impede productivity and raise serious privacy flags.

Addressing Privacy Concerns with Mandatory File Uploads to External Servers

One of the most significant concerns for users, especially those handling confidential or sensitive documents, is the requirement to upload files to external servers. Adobe Acrobat Online, like many other online PDF tools, operates on a server-side processing model. This means that when you want to merge PDFs, your files must first leave your device, travel across the internet, reside temporarily on Adobe's infrastructure, be processed, and then be downloaded back to you.

This process introduces several privacy risks:

Data Vulnerability: While companies like Adobe employ security measures, any time your data is transmitted and stored on a third-party server, it becomes a potential target for data breaches or unauthorized access. For documents containing personal information, financial data, or proprietary business secrets, this risk is simply unacceptable.

Jurisdictional Issues: Where are these servers located? What data protection laws apply to them? These questions often go unanswered, leaving users in the dark about the legal protections (or lack thereof) for their sensitive information.

Temporary Storage: Even if files are deleted after processing, there's a window during which they exist on an external server, creating a point of vulnerability. For users seeking a "free Adobe Acrobat online alternative," this is a non-starter.

Frustration with Adobe's Freemium Model and Feature Gating for Essential Tasks

Adobe Acrobat Online employs a classic freemium business model. While it offers some basic tools for "free," the reality is that many essential features are locked behind a paid subscription. Users frequently encounter:

Limited Usage: You might be able to merge a couple of PDFs, but then you hit a wall, prompted to subscribe for unlimited use.

File Size Restrictions: Larger documents often exceed the limits of the free tier, forcing an upgrade or a search for another tool.

Feature Gating: Advanced options, like specific page reordering, compression, or removal, might be reserved for premium users, turning what should be a straightforward task into a frustrating experience.

Constant Upselling: The user experience is often interrupted by persistent prompts to sign up or upgrade, disrupting workflow and undermining the promise of a "free" tool. This constant friction is a key reason why users actively seek a truly free Adobe Acrobat online alternative.

Avoiding Account Creation and Personal Data Submission for Simple PDF Operations

To access the full suite of Adobe Acrobat Online's free tools, or to bypass initial usage limits, users are often required to create an Adobe account. This adds unnecessary friction and demands personal information for what should be an anonymous, quick task:

Time Consumption: Creating an account takes time and effort, demanding an email address, password, and sometimes even more personal details.

Data Collection: Every account creation is an opportunity for companies to collect user data, track usage patterns, and build profiles, which many users prefer to avoid for simple, one-off tasks.

Login Dependency: Tying usage to a login means you can't just jump in and use the tool anonymously, which is a major draw for many online utility users.

Overcoming Slow Processing Times Due to Server-Side Dependencies and Internet Latency

Because files are uploaded, processed on Adobe's servers, and then downloaded, the merging process can be significantly slower, especially with larger files or during peak usage times. This server-dependent architecture introduces latency that client-side tools avoid:

Internet Speed Dependency: Your merge speed is directly tied to your internet upload and download speeds. A slow connection means a slow process.

Server Load: During busy periods, Adobe's servers can experience high loads, leading to queues and further delays in processing your documents.

Unnecessary Data Transfer: Even for small changes, the entire document must be uploaded and downloaded, consuming bandwidth and time.

These cumulative frustrations underscore the urgent need for a "free Adobe Acrobat online alternative" that respects user privacy, offers genuine freedom, and delivers instant performance.

ShowPro Merge PDF: The Truly Free, Private, and Instant Solution

ShowPro's Merge PDF tool stands as the definitive "free Adobe Acrobat online alternative," meticulously engineered to address every one of the aforementioned pain points. We've built a solution that redefines what "free" truly means in the realm of online PDF utilities.

Introducing ShowPro's 100% Browser-Based Processing for Ultimate Privacy

At the core of ShowPro's offering is our commitment to ultimate user privacy. Our Merge PDF tool operates entirely within your web browser. This means that from the moment you select your files to the second you download your merged document, your PDFs never leave your device. All processing, manipulation, and merging occur client-side, leveraging the power of modern web technologies. This fundamental design choice makes ShowPro an unparalleled "free Adobe Acrobat online alternative" for privacy-conscious users.

Highlighting Zero File Uploads – Files Never Leave Your Device

This isn't just a feature; it's a foundational principle. When you use ShowPro Merge PDF, there are absolutely no file uploads to our servers. Your documents remain local, confined to the secure environment of your own browser. This eliminates the privacy risks associated with server-side processing, making ShowPro the ideal choice for sensitive documents that simply cannot be exposed to external infrastructure. For those seeking a truly secure "free Adobe Acrobat online alternative," this is a non-negotiable benefit.

Emphasizing Unlimited Use Without Any Sign-Up or Hidden Costs

Forget about freemium models, feature gating, or hidden costs. ShowPro's Merge PDF is 100% free, 100% of the time. There are no subscriptions to sign up for, no premium tiers to unlock, and no sneaky charges. We believe that essential PDF tools should be universally accessible without financial barriers. This commitment to genuine freeness sets ShowPro apart as a superior "free Adobe Acrobat online alternative."

Showcasing Immediate Results Thanks to Client-Side Execution

Because your files never leave your browser, the merging process with ShowPro is virtually instantaneous. There's no waiting for uploads, no server queues, and no downloads. The moment you arrange your PDFs and click "Merge," the process completes in seconds, limited only by your device's processing power. This immediate feedback and rapid execution provide a seamless, efficient user experience that server-dependent tools simply cannot match, making ShowPro a truly instant "free Adobe Acrobat online alternative."

Unpacking the Privacy Advantage: ShowPro vs. Adobe Acrobat Online

When it comes to handling your documents, privacy isn't just a feature – it's a fundamental right. ShowPro's Merge PDF tool is built from the ground up with this principle in mind, offering a privacy model that stands in stark contrast to Adobe Acrobat Online and positions us as the leading "free Adobe Acrobat online alternative" for security-conscious users.

Detailed Explanation of How Files Remain on the User's Device (WebAssembly)

The magic behind ShowPro's unparalleled privacy lies in its innovative use of WebAssembly (Wasm). Instead of sending your PDF files to a remote server, ShowPro executes the entire PDF merging process directly within your web browser. When you load our tool, the necessary code – including the powerful pdf-lib.js library – is downloaded to your browser. This code, compiled into WebAssembly, runs at near-native speed, allowing for complex PDF manipulations locally.

Here's how it works:

Local File Access: You select your PDF files from your device. The browser grants the web page temporary, sandboxed access to these files.

In-Browser Processing: The WebAssembly code reads the raw PDF byte streams of your selected documents. It then parses their internal structure, including cross-reference tables and compressed objects, all within your browser's memory.

Merging Logic: The pdf-lib.js library, running via WebAssembly, performs the actual merging. It combines the PDF objects, updates the document catalog, and reconstructs the PDF's internal structure (conforming to the PDF spec, ISO 32000-2) to create a single, cohesive merged document.

Instant Download: Once the new PDF is generated, it's immediately available for download to your device, never having touched an external server.

This entire workflow ensures that your sensitive data, contained within the PDF byte streams, remains exclusively on your device, protected by your browser's security sandbox.

ShowPro's Inherent GDPR, HIPAA, and CCPA Compliance by Design

Because ShowPro operates with zero server uploads and zero data collection, it is inherently compliant with major global privacy regulations like GDPR (General Data Protection Regulation), HIPAA (Health Insurance Portability and Accountability Act), and CCPA (California Consumer Privacy Act).

GDPR: No processing of personal data on our servers means no need for complex data processing agreements or concerns about international data transfers.

HIPAA: For healthcare professionals or anyone handling Protected Health Information (PHI), the assurance that files never leave the browser is critical for maintaining patient confidentiality. ShowPro provides a safe environment for merging sensitive medical records without risking HIPAA violations.

CCPA: Californian consumers can rest assured that their personal information, embedded in their PDFs, is not being collected, sold, or shared by ShowPro.

This "privacy by design" approach makes ShowPro a truly safe "free Adobe Acrobat online alternative" for organizations and individuals alike.

No Data Retention, No Server Logs, No Tracking of User Documents

ShowPro's commitment to privacy extends beyond just not uploading your files. We collect absolutely no personal information, maintain no server logs of your activity, and certainly do not track the content of your documents. Your usage is anonymous and untraceable. This contrasts sharply with services that might log IP addresses, usage patterns, or even metadata from uploaded files, even if they claim not to "store" your documents long-term. With ShowPro, your digital footprint for PDF merging is effectively zero.

The Security Implications of Client-Side Processing Compared to Server-Based Uploads

The security implications of client-side processing are profound:

Elimination of Transmission Risk: Data breaches often occur during transmission or when data is at rest on a server. By keeping files local, ShowPro eliminates these vulnerabilities entirely.

Reduced Attack Surface: Our servers handle only the website code, not your sensitive documents. This significantly reduces our attack surface, as there's no user data for malicious actors to target on our infrastructure.

Browser Sandbox Security: Modern web browsers provide robust sandboxing environments, isolating web applications from your operating system and other applications. This adds another layer of security, ensuring that even if there were a vulnerability in our client-side code, it would be contained.

In essence, ShowPro provides a fortress of privacy for your PDF merging needs, making it the most secure "free Adobe Acrobat online alternative" available.

Performance & Accessibility: Browser-Based Speed vs. Server-Side Delays

Beyond privacy, the immediate, tangible benefit of ShowPro's client-side architecture is its superior performance and universal accessibility, a stark contrast to the often sluggish and restricted experience of server-dependent tools like Adobe Acrobat Online.

How Client-Side Execution Enables Instant PDF Merging, Regardless of Internet Speed (Post-Load)

Once the ShowPro Merge PDF page has loaded in your browser, your internet connection speed becomes largely irrelevant to the merging process itself. The WebAssembly-powered pdf-lib.js library, already downloaded to your device, performs all the heavy lifting locally. This means:

No Upload/Download Bottlenecks: The most time-consuming parts of server-side processing – uploading large PDF files and then downloading the merged result – are completely eliminated.

Consistent Speed: Your merging speed is primarily determined by your device's CPU, not by fluctuating internet bandwidth or server load. This ensures a consistent, rapid experience every time, whether you're on a blazing-fast fiber connection or a slower mobile hotspot.

Real-time Feedback: You see the results almost instantly, allowing for rapid iterations if you need to reorder pages or make adjustments. This level of responsiveness is a hallmark of a truly efficient "free Adobe Acrobat online alternative."

Accessibility Across Any Modern Browser and Operating System Without Software Installs

ShowPro's Merge PDF is a web-based application, meaning it runs seamlessly across any modern web browser (Chrome, Firefox, Edge, Safari, Opera, Brave, etc.) and any operating system (Windows, macOS, Linux, Android, iOS).

No Software Downloads: Unlike desktop PDF editors or even some online tools that might require specific browser extensions, ShowPro works out of the box. There's nothing to download, install, or update on your system.

Universal Compatibility: This universal accessibility makes ShowPro an incredibly convenient "free Adobe Acrobat online alternative" for users who switch between devices, work on different operating systems, or simply prefer not to clutter their machines with additional software.

Lightweight Footprint: The tool itself is lightweight, ensuring a smooth experience even on older hardware, as long as it can run a modern browser.

The Lightweight and Efficient Nature of ShowPro's WebAssembly-Powered Tools

WebAssembly is designed for high performance and efficiency. It allows complex applications, traditionally limited to desktop software, to run directly in the browser with near-native speeds.

Optimized Code: The pdf-lib.js library, compiled to WebAssembly, is highly optimized for PDF manipulation, handling PDF byte streams, cross-reference tables, and object compression with incredible speed.

Resource Efficiency: WebAssembly operations are efficient in terms of CPU and memory usage, ensuring that your browser remains responsive and doesn't hog system resources during the merging process.

Comparing the Latency of Uploading/Downloading with the Immediacy of Local Processing

Let's illustrate the difference:

Adobe Acrobat Online (Server-Side):

1. Select files (local).

2. Upload files to server (latency: seconds to minutes, depending on size/internet).

3. Server processes files (latency: seconds, depending on server load).

4. Download merged file from server (latency: seconds to minutes).

5. Total time: Significant, variable, and dependent on external factors.

ShowPro Merge PDF (Client-Side):

1. Select files (local).

2. Process files in browser (latency: milliseconds to a few seconds, depending on CPU/file size).

3. Download merged file (instant, as it's already local).

4. Total time: Minimal, consistent, and primarily dependent on your device.

This fundamental difference in architecture makes ShowPro a dramatically faster and more reliable "free Adobe Acrobat online alternative" for anyone who values their time and efficiency.

ShowPro vs Free Adobe Acrobat Online: Side-by-Side Comparison

| Feature | Showpro | Adobe-Acrobat-Online |

| --- | --- | --- |

| Price | 100% Free (no hidden costs) | Freemium (paid subscription for full features) |

| Privacy / File Upload | Files never leave your browser (100% client-side) | Requires file upload to server |

| Speed | Instant (browser-based processing) | Server-dependent (can be slow due to upload/download) |

| File Size Limit | Unlimited (limited only by browser/device memory) | Often limited in free tier |

| Account Required | No account, no signup ever | Yes, for full features or after limited uses |

| Output Quality | Original quality, no watermarks | High (but watermarks possible in free tier) |

Why Switch to ShowPro? Five Concrete Benefits Over Adobe's Free Tier

Choosing ShowPro as your "free Adobe Acrobat online alternative" isn't just about avoiding Adobe's drawbacks; it's about embracing a superior, user-centric experience that offers genuine value and freedom. Here are five concrete benefits that elevate ShowPro above Adobe's free offering:

No Watermarks on Merged PDFs, Ensuring Professional Output: Unlike many "free" PDF tools, including sometimes Adobe's own free tier, ShowPro never imposes watermarks on your merged documents. Your output will be clean, professional, and ready for any use, preserving the original integrity and appearance of your PDFs without any intrusive branding. This is crucial for business documents, academic papers, or personal records where a professional presentation is paramount.

Absolutely No File Size Limits or Usage Caps: ShowPro breaks free from the restrictive constraints of freemium models. You can merge PDFs of any size, limited only by your browser's and device's memory. There are no daily, weekly, or monthly usage caps. Whether you're combining two small documents or dozens of large, image-heavy PDFs, ShowPro handles it all without asking for an upgrade. This truly unlimited usage makes it an indispensable "free Adobe Acrobat online alternative."

Consistent, High-Quality Output That Preserves Original Document Integrity: Our client-side processing, powered by robust WebAssembly libraries, ensures that your merged PDFs maintain their original quality, formatting, fonts, and images. There's no server-side re-rendering that could introduce subtle changes or quality degradation. What you put in is what you get out, just combined seamlessly, adhering to the PDF spec (ISO 32000-2).

Access to 200+ Other Free, Privacy-Focused Tools Within the ShowPro Suite: ShowPro isn't just about merging PDFs. We offer a comprehensive suite of over 200 other privacy-first, browser-based tools, all operating under the same principles of no uploads, no accounts, and no cost. Need to reduce a file size? Try our [Compress PDF](https://showprosoftware.com/tools/compress-pdf) tool. Converting formats? We have [PDF to JPG](https://showprosoftware.com/tools/pdf-to-jpg) and [JPG to PDF](https://showprosoftware.com/tools/jpg-to-pdf). For text-heavy documents, our [PDF to Word Converter](https://showprosoftware.com/tools/pdf-to-word) is invaluable. And if you need to clean up a document, our [PDF Page Remover](https://showprosoftware.com/tools/remove-pdf-pages) is ready. This vast ecosystem of tools makes ShowPro a holistic "free Adobe Acrobat online alternative" for all your document needs.

No Account, Truly Anonymous Usage: With ShowPro, your privacy is paramount. You can use our Merge PDF tool, and indeed all our tools, without ever creating an account, providing an email, or sharing any personal information. Your activity is completely anonymous, offering a level of privacy and freedom that Adobe Acrobat Online's account-driven model simply cannot match.

Beyond Merging: How ShowPro Outperforms Adobe's Free Tier

While our Merge PDF tool is a stellar "free Adobe Acrobat online alternative" for combining documents, ShowPro's value proposition extends far beyond this single utility. Our entire platform is designed to offer a comprehensive, unencumbered experience that consistently outperforms the limitations of Adobe's free tier across a spectrum of PDF and document management tasks.

As highlighted, ShowPro ensures no watermarks on your merged PDFs, guaranteeing a professional and unbranded output. This is a critical distinction, as many "free" online tools, including some aspects of Adobe's free offering, often embed watermarks as a subtle nudge towards their paid subscriptions. With ShowPro, your documents remain pristine, reflecting only your content.

Furthermore, we impose absolutely no file size limits or usage caps. This freedom is a game-changer. Imagine needing to merge a dozen large reports, each several hundred megabytes. With Adobe's free tier, you'd likely hit a size limit or a "you've used your free merges" message, forcing you to upgrade or find another tool. ShowPro, limited only by your device's capabilities, lets you merge as many and as large PDFs as you need, without interruption. This commitment to unlimited access truly positions us as the superior "free Adobe Acrobat online alternative."

Our commitment to consistent, high-quality output means that the integrity of your original documents is always preserved. Fonts, images, layouts, and interactive elements are meticulously maintained during the merging process, thanks to our client-side WebAssembly engine. There's no risk of server-side conversion errors or rendering inconsistencies that can sometimes plague external processing services.

But ShowPro's true power as a "free Adobe Acrobat online alternative" lies in its expansive ecosystem of tools, all built on the same privacy-first, client-side foundation:

[Compress PDF](https://showprosoftware.com/tools/compress-pdf): Easily reduce the file size of your PDFs without compromising quality, making them easier to share via email or upload to websites. This is a common need that Adobe often gates behind a premium.

[PDF to JPG](https://showprosoftware.com/tools/pdf-to-jpg): Convert individual PDF pages into high-quality JPG images, perfect for presentations, web use, or sharing snippets.

[JPG to PDF](https://showprosoftware.com/tools/jpg-to-pdf): Combine multiple JPG images into a single PDF document, ideal for creating portfolios or multi-page documents from scanned images.

[PDF to Word Converter](https://showprosoftware.com/tools/pdf-to-word): Transform your PDFs into editable Word documents, saving you countless hours of manual retyping. This is a premium feature for most competitors.

[PDF Page Remover](https://showprosoftware.com/tools/remove-pdf-pages): Quickly delete unwanted pages from your PDF documents, allowing for precise control over your content.

Each of these tools operates with the same privacy guarantees: files never leave your browser, no accounts are needed, and there are no hidden costs. This integrated approach means you have a comprehensive, powerful, and genuinely free toolkit at your fingertips, far surpassing the limited, often frustrating, experience offered by Adobe's free tier. ShowPro isn't just an alternative; it's an upgrade to how you manage your documents online.

Technical Deep Dive: Client-Side Processing with WebAssembly & Canvas API

Understanding the technical underpinnings of ShowPro's Merge PDF tool reveals why it's not just a convenient "free Adobe Acrobat online alternative," but a fundamentally more secure and efficient one. Our architecture leverages cutting-edge web technologies to deliver a desktop-like experience directly in your browser.

Explaining the Role of WebAssembly for High-Performance PDF Manipulation Directly in the Browser

WebAssembly (Wasm) is a binary instruction format for a stack-based virtual machine. It's designed as a portable compilation target for high-level languages like C, C++, and Rust, enabling deployment on the web for client and server applications. For ShowPro, Wasm is critical for achieving high-performance PDF manipulation directly in the browser.

Here's how it works for PDF merging:

Near-Native Speed: PDF manipulation, especially parsing complex structures like the PDF spec (ISO 32000-2), handling PDF byte streams, cross-reference tables, and object compression, is computationally intensive. By compiling a robust PDF library (like pdf-lib.js which ShowPro utilizes) to WebAssembly, we can execute these operations at speeds comparable to native desktop applications. This bypasses the performance limitations typically associated with JavaScript for such tasks.

Efficient Memory Management: WebAssembly provides low-level memory control, allowing for more efficient handling of large PDF files and their internal data structures directly within the browser's memory. This prevents the browser from becoming sluggish or crashing, even with multi-gigabyte files (within reasonable browser/device limits).

Complex Algorithm Execution: Merging PDFs involves intricate algorithms to combine document objects, resolve references, and update metadata. WebAssembly is perfectly suited for executing these complex algorithms rapidly and reliably, ensuring the integrity and quality of the final merged document.

This powerful combination of WebAssembly and pdf-lib.js means that ShowPro can perform sophisticated PDF operations without ever needing to send your data to a server, making it a truly private and high-performance "free Adobe Acrobat online alternative."

How the Canvas API is Utilized for Rendering and Visual Integrity of PDF Pages

While WebAssembly handles the data manipulation, the HTML5 Canvas API plays a crucial role in the visual aspect of PDF processing, particularly for rendering and ensuring visual integrity during tasks like page reordering or previewing.

Visual Previews: When you drag and drop PDFs into ShowPro's merger, or reorder pages, the Canvas API can be used to render small, high-fidelity previews of each PDF page. This allows you to visually confirm your selections and arrangements before finalizing the merge.

Page Manipulation: If the tool offers features like rotating individual pages or cropping, the Canvas API would be instrumental in displaying these changes in real-time without server interaction.

Image Extraction/Embedding: For tools that convert PDFs to images (like our [PDF to JPG](https://showprosoftware.com/tools/pdf-to-jpg) tool) or vice-versa (like [JPG to PDF](https://showprosoftware.com/tools/jpg-to-pdf)), the Canvas API is often used to draw and manipulate image data directly in the browser before embedding it into a new PDF or extracting it from an existing one.

This client-side rendering capability ensures that the visual output is accurate and immediate, further enhancing ShowPro's efficiency as a "free Adobe Acrobat online alternative."

The Robust Security Framework Provided by Modern Browser Sandboxing

Modern web browsers are incredibly sophisticated security environments. They employ a concept called "sandboxing," which isolates web pages from your operating system and from each other.

Process Isolation: Each browser tab or web application typically runs in its own isolated process. This means that even if a vulnerability were found in a specific web application, it would be contained within that sandbox and unable to access other parts of your system or other browser tabs.

Restricted File Access: Web applications, by default, have very limited access to your local file system. When you select files for ShowPro's Merge PDF, the browser grants the application temporary, highly restricted access to *only* those specific files, and only for the duration of your interaction. The application cannot browse your hard drive or access other personal data.

No Persistent Storage: Unless explicitly allowed (e.g., through local storage APIs, which ShowPro doesn't use for document content), web applications cannot permanently store data on your device without your consent. This means your PDF content is processed in memory and then discarded once the tab is closed or the process is complete.

Why This Modern Tech Stack Ensures Both Speed and Data Security

The combination of WebAssembly, the Canvas API, and browser sandboxing creates a powerful and secure environment for PDF processing:

Uncompromised Privacy: By keeping all processing client-side, files never leave your device. This inherently safeguards your data from server breaches, unauthorized access, and compliance issues. No server upload means it's inherently GDPR, HIPAA, and CCPA safe for even the most sensitive documents.

Exceptional Performance: WebAssembly delivers near-native speeds for computationally intensive tasks, ensuring quick and responsive PDF manipulation.

Enhanced Security: Browser sandboxing provides a robust layer of defense, isolating the web application and preventing malicious actions from impacting your system.

Reliability: The direct, local processing eliminates dependencies on external servers, network latency, and server load, leading to a more consistent and reliable user experience.

This sophisticated yet user-friendly technical approach is what makes ShowPro the truly advanced and trustworthy "free Adobe Acrobat online alternative" for all your PDF merging needs.

Making the Switch: Your Guide to ShowPro's Merge PDF

Transitioning from the often-frustrating experience of Adobe Acrobat Online to ShowPro's seamless Merge PDF tool is incredibly straightforward. You'll find that our interface is designed for immediate usability, requiring no learning curve or prior experience. Here’s a simple, step-by-step guide to get started:

Visit the ShowPro Merge PDF Tool: Open your web browser and navigate directly to [https://showprosoftware.com/tools/merge-pdf](https://showprosoftware.com/tools/merge-pdf). You'll be greeted with a clean, intuitive interface, free from ads or distracting pop-ups.

Simple Drag-and-Drop Interface for Effortless File Selection:

* Drag & Drop: The easiest way to add your PDFs is to simply drag them from your desktop or file explorer directly into the designated drop zone on the ShowPro page.

* Click to Select: Alternatively, click the "Select Files" button. This will open your device's file browser, allowing you to navigate to and select multiple PDF documents you wish to merge.