Merge PDF — Combine Multiple PDFs into One Free Online
Combine any number of PDF files into a single document — entirely in your browser, with no upload and no account required. Drag and drop to reorder files, choose your output page size (A3, A4, A5, Letter, or Legal), and set portrait or landscape orientation. A live summary shows the total page count per file before you merge. Powered by PDF-lib. Free forever.
Merge Summary
How to Merge PDF Files
Alfreto's PDF Merger uses PDF-lib — a JavaScript library running entirely in your browser — to copy pages from each source PDF and combine them into a new document. No file is ever sent to any server. The entire operation happens locally on your device.
Step 1 — Add Your PDF Files
Click Choose PDFs or drag and drop multiple PDF files into the drop zone at once. Each file is read locally — page count and file size are shown immediately in the list. You can add more files at any time, including after you have already reordered the list. Password-protected PDFs are automatically skipped with a warning.
Step 2 — Set the Order
The order of files in the list is the order pages will appear in the merged PDF. To change the order, drag and drop any file row to a new position, or use the ↑ ↓ arrow buttons on each row. The Merge Summary panel on the right updates live to show the current sequence, total page count, and total file size as you reorder.
Step 3 — Choose Output Page Size and Orientation
Use the options below the file list to control the output page dimensions:
- As-is (original) — Each page keeps its original dimensions. Best when all source PDFs are already the same size.
- A4 / A3 / A5 — Standardizes all pages to the selected ISO paper size. Page content is scaled and centered to fit.
- Letter / Legal — Standardizes to US paper sizes. Useful when sharing with North American systems or printing on standard office paper.
- Orientation — Choose Portrait, Landscape, or keep each page's original orientation. When a target size is selected, pages that are landscape in the source will be rotated to match if you choose "As-is orientation".
Step 4 — Merge and Download
Click Merge PDFs. A progress bar tracks each file as it is copied into the merged document. When complete, click Download .pdf to save the file — it is named merged.pdf automatically. The status bar shows the total page count and output settings after merging.
Common Use Cases
- Combining report chapters — Merge separately authored chapters or sections into a single PDF for submission or distribution.
- Assembling application documents — Combine a CV, cover letter, and certificates into one PDF for a job or university application.
- Merging scanned pages — Join multiple single-page scans into a multi-page document for archiving or email.
- Consolidating invoices — Combine monthly invoices or receipts into a single PDF for accounting or tax purposes.
- Standardizing mixed-size PDFs — Merge PDFs of different page sizes (e.g. A4 and Letter) and output them all as A4 for consistent printing.
Frequently Asked Questions
Are my PDFs uploaded to a server when I merge them?
No — your files never leave your device. The tool uses PDF-lib, a JavaScript library running entirely inside your browser tab. No data is sent over the internet at any point. This makes it completely safe for confidential documents such as contracts, personal records, financial statements, and medical files.
How do I control the order pages appear in the merged PDF?
The file list order determines the page order in the merged output. Drag and drop any row to reposition it, or use the ↑ ↓ buttons. The Merge Summary on the right updates in real time to reflect the current order, showing each file's name and page count in the final sequence.
Can I merge PDFs of different page sizes?
Yes. By default, each page keeps its original dimensions (As-is). If you want a consistent output, select a target page size — A3, A4, A5, Letter, or Legal — and the tool will scale all pages to fit that size while preserving the content. You can also force a single orientation (portrait or landscape) for the entire merged document.
Is there a limit on how many PDFs I can merge?
There is no hard file count limit. However, merging many large PDFs may be slower depending on your device's available memory and CPU speed. For most typical documents (under 50 MB total), merging completes in a few seconds. Very large collections (hundreds of pages, embedded images) may take longer.
Will the content, fonts, and images in my PDFs be preserved?
Yes. PDF-lib copies pages from each source document into the merged output, preserving text, fonts, images, and vector graphics. Some advanced PDF features — such as interactive form fields, JavaScript actions, and document-level bookmarks — may not be carried over into the merged file, as PDF-lib merges page content rather than the full document structure.
Can I merge password-protected PDFs?
No. Encrypted or password-protected PDFs cannot be loaded by PDF-lib without the correct password, and the file will be skipped automatically with a warning. Remove the password first using your PDF viewer (Adobe Reader, Chrome, Preview on Mac), then add the unprotected file to the merger.
What does "output page size" do?
When you select a target page size (e.g. A4), all pages in the merged PDF are resized to that standard. The page content is scaled proportionally and centered to fit the new dimensions. The original source PDFs are not modified — only the merged output uses the selected size. This is useful when combining PDFs from different sources that have inconsistent page sizes.
Can I remove a file from the list after adding it?
Yes. Each file in the list has a ✕ button to remove it individually. There is also a Clear all button at the top of the list to remove all files at once and start fresh.
Why Use Alfreto to Merge PDFs?
Most online PDF mergers upload your files to a remote server, which creates a privacy risk and introduces upload wait times. Alfreto's merger runs entirely in your browser — processing is instant, completely private, and free with no file count limits or daily quotas.