Combine multiple PDF files into a single document with drag-and-drop reordering
Drag & drop files here
or click to browse
Accepted: .pdf
Large file performance?
Browser local processing works best on Desktop for files over 100MB.
Securely merge PDF documents on Windows, Mac, or Linux without any server dependencies. FileMint uses client-side PDF.js and WebAssembly to concatenate multiple documents by copying their page objects into a unified page tree. This process involves merging resource dictionaries—including fonts, images, and form XObjects—and rebuilding the cross-reference table (xref) with updated byte offsets directly in your browser. Unlike traditional server-based tools, your confidential files (like legal contracts or medical records) never leave your device, eliminating the risk of data leaks or third-party storage. Our architecture resolves shared resources to optimize output file size and preserves vector graphics, text layers, and hyperlinks for professional-grade results.
Learn more about this tool and related topics in our blog.
Stop uploading sensitive documents to random servers. Learn how to manage, edit, and convert PDFs entirely in your browser without sacrificing privacy or performance.
Merge PDFs securely, privately, and instantly—right in your browser. No uploads, no data risks, just lightning-fast, 100% offline document combining.
Unlock unparalleled data privacy with Filemint. Discover how our "Offline First" approach processes your sensitive files directly in your browser, ensuring they never leave your device. Experience true security and peace of mind.
This tool uses client-side WebAssembly to ensure your data never touches a server. Secure, fast, and 100% private by design.
Initial Loading: Select your PDF files via the system picker or drag-and-drop. Our FileReader implementation reads each file as an ArrayBuffer, keeping the data strictly in your browser's private memory space.
Document Parsing: PDF.js (Mozilla's open-source library) parses the document catalog of each file to reconstruct its internal page tree. We identify individual /Page objects and their associated /Resources.
Sequence Arrangement: Arrange your documents in the exact order you need. Our React-based state manager maintains a real-time index of your files, allowing for instant reordering before the final concatenation.
Binary Concatenation: When you click 'Merge', our WebAssembly-accelerated engine copies content streams and resources (fonts, images, XObjects) into a new unified PDF structure, resolving any object ID conflicts.
Final Construction: We rebuild the Cross-Reference Table (xref) and generate a new trailer, ensuring the final PDF is valid according to international standards before prompting a local browser download.
Merge multi-part contract into one
contract_part1.pdf, part2.pdf, part3.pdf
complete_contract.pdf - all sections in one file
Create yearly report from monthly PDFs
Jan.pdf, Feb.pdf... Dec.pdf (12 files)
annual_report_2024.pdf - single document!
Combine resume, cover letter, references
resume.pdf, cover_letter.pdf, references.pdf
job_application.pdf - ready to submit
Combine all contract documents for court/legal filing.
Consolidate department reports into one.
Combine chapters into complete book.
Combine multiple invoices for accounting.
Merging PDF documents is a universal requirement for business and academic workflows. On Windows, users often resort to complex software like Adobe Acrobat or unsecured web services. FileMint provides a native-speed alternative using your browser's V8 or SpiderMonkey engine. To merge on Windows, simply drag your files from File Explorer into our drop zone. For macOS users, while Preview offers basic merging, our tool provides a more intuitive drag-and-drop interface for bulk operations and reordering. The process is identical: your OS handles the file selection, and our WebAssembly modules handle the binary concatenation without ever needing a network connection.
Traditional 'cloud' PDF tools require you to upload your documents to their servers. This creates a massive security vulnerability: your files (which often contain SSNs, signatures, or trade secrets) are stored on a third-party server, sometimes indefinitely. FileMint's client-side architecture eliminates this risk entirely. By using the JavaScript File API, we read your documents into a localized 'sandbox' in your browser memory. The merging algorithm executes locally, and the resulting blob is generated on your own hardware. Even if you disconnect your internet after the page loads, the tool continues to function—proving that zero data is being transmitted to the cloud.
Behind the scenes, FileMint doesn't just 'glue' files together. We perform a sophisticated 'Page Tree Concatenation'. Each PDF has a root object called a 'Catalog' which points to a 'Pages' node. Our engine traverses the object trees of all input PDFs, re-mapping indirect object references to prevent ID collisions. We then construct a brand new Page Tree that links to the original page objects. This ensures that features like internal hyperlinks, annotations, and form fields are preserved whenever possible. We also handle Cross-Reference Table (xref) generation, ensuring the final file is optimized and follows the ISO 32000-1 specification for PDF portability.
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Learn more about this tool and related topics in our blog.
Stop uploading sensitive documents to random servers. Learn how to manage, edit, and convert PDFs entirely in your browser without sacrificing privacy or performance.
Merge PDFs securely, privately, and instantly—right in your browser. No uploads, no data risks, just lightning-fast, 100% offline document combining.
Unlock unparalleled data privacy with Filemint. Discover how our "Offline First" approach processes your sensitive files directly in your browser, ensuring they never leave your device. Experience true security and peace of mind.
