Merge PDF Files Online — Free, Fast & 100% Private
Combine two or more PDF documents into a single file directly in your browser. No uploads, no signup, no watermarks. Last updated: January 2026.
PDF Merger
Select 2 or more PDF files to combine them into one document.
Why use AlllinTools to merge PDFs?
Most online PDF mergers upload your files to a remote server. For confidential contracts, tax documents, medical records, and personal scans, that's a privacy problem. AlllinTools runs entirely in your browser using the open-source pdf-lib library. Your files never leave your device.
🔒 100% Private
Files are processed locally. Nothing is sent to any server, ever.
⚡ Instant Processing
Merging happens in seconds because there's no upload or download wait.
🆓 No Limits
Merge unlimited PDFs per day. No subscription, no signup, no email required.
📱 Works Everywhere
Runs on any modern browser — Windows, Mac, Linux, iPhone, Android.
🎯 Lossless Quality
Original text, images, fonts, and layout are preserved exactly.
🚫 No Watermarks
Your merged PDF is clean — no logos or promotional text added.
How to merge PDF files in 4 steps
- Click the file selector above. A file picker will open. Hold Ctrl (Windows) or Cmd (Mac) to select multiple PDFs at once.
- Choose your files in the order you want them combined. The first file you select becomes the first section of the merged PDF.
- Click the "Merge PDFs" button. Processing happens instantly in your browser — you'll see a status indicator.
- Download the merged file. A download link will appear once the merge is complete. Save it to your device with a click.
Common reasons to merge PDF files
- Job applications: Combine your resume, cover letter, and certificates into one professional document.
- Invoices and receipts: Consolidate monthly invoices into a single file for accounting or tax submission.
- Academic submissions: Bundle research papers, references, and appendices into one deliverable.
- Legal documents: Merge contracts, signed pages, and exhibits into a single archive-ready file.
- Scanned book chapters: Combine separately-scanned chapters of a textbook or notebook into one PDF.
- Real estate paperwork: Combine purchase agreements, disclosures, and inspection reports for buyers and lenders.
- Medical records: Bundle lab results, prescriptions, and reports from different providers into a single file for a doctor visit.
Tips for better PDF merging
Reorder files before selecting
Some browsers select files alphabetically. To ensure correct order, rename your PDFs with a number prefix (01-cover.pdf, 02-resume.pdf, 03-references.pdf) before selecting them.
Reduce file size first if needed
If your merged file is too large to email, run each PDF through our image compressor if it contains scanned images, or split very large PDFs first with our PDF splitter.
Remove passwords before merging
Encrypted PDFs cannot be combined until they're unlocked. Use the original document's password to remove encryption first, then merge.
Frequently asked questions
Is the AlllinTools PDF merger really free?
Yes. The PDF merger is completely free with no hidden fees, no signup, no daily limits, and no watermarks added to your merged file.
Are my PDF files uploaded to a server?
No. All merging happens locally inside your web browser using JavaScript. Your files never leave your computer, which makes this tool safe for confidential and sensitive documents.
How many PDF files can I merge at once?
There is no hard limit. You can typically merge 20 to 50 PDFs at once depending on file sizes and your device's available memory. For very large files (over 100 MB total), merging in smaller batches is recommended for best performance.
Will merging reduce the quality of my PDFs?
No. The merger uses lossless processing, meaning your text, images, fonts, and formatting are preserved exactly as they appear in the original files.
Can I merge password-protected PDFs?
Password-protected PDFs cannot be merged until they are unlocked. You will need to remove the password from each PDF before merging them.
Does this work on mobile phones and tablets?
Yes. The PDF merger works on any modern browser including Chrome, Safari, Firefox, and Edge on Windows, macOS, Linux, Android, and iOS.
In what order will my PDFs be combined?
PDFs are merged in the order you selected them. If you need a specific sequence, select your files in that exact order from the file picker.
Is there a file size limit?
There is no fixed server limit because processing is done in your browser. Performance depends on your device's RAM. Most users can comfortably merge files totaling 200 MB or more.