About this Merge PDF
Combine multiple PDF files into one document with our merge pdf tool. Drag and drop, arrange in the order you want, then download a single merged PDF — all in your browser, no upload of your selected files to any server.
This online merge pdf tool works on any device with a modern browser: Windows, Mac, Linux, Chromebook, iPhone, iPad, and Android. Because everything runs locally using JavaScript and the pdf-lib library, your selected files are processed in your browser and are not uploaded to our server. There’s no size limit other than what your device’s memory can handle, and there is no watermark added to your output.
Your privacy is the default. Your selected files are processed in your browser and are not uploaded to our server. This merge operation runs client-side using pdf-lib. Other PDF Tools Base tools use PDF.js, jsPDF, JSZip, and Tesseract.js where needed. Closing the tab clears the working session from this page; downloaded files remain on your device.
This tool is free to use with no signup required. Large files may be limited by your browser’s memory and device performance. Part of PDF Tools Base, a privacy-first collection of 161 PDF utilities. Bookmark the page for next time, and explore related tools in the footer below.
When to choose Merge Pdf
This tool is for people assembling a few separate PDF files — an invoice, a signed contract, and a cover letter, say — into one document to send or archive.
Worked example: Suppose you have quote.pdf, signed-agreement.pdf and terms.pdf. Add all three, drag quote.pdf to the top so it leads, then download a single ordered file ready to email.
Merge PDF and Combine PDF run the same client-side join; reach for Merge when you are stitching a handful of different documents together and the running order matters.
- Arrange before you export — the download follows the on-screen order top to bottom.
- If one source is itself several pages, it keeps its internal order inside the merged file.
Does merging change the original files?
No. The tool reads each file in your browser and writes a new combined PDF; your source files stay exactly as they were on disk.
Can I merge PDFs of different page sizes?
Yes. A4, Letter and custom sizes can sit in the same merged document — each page keeps its own dimensions.
Frequently asked questions
Is Merge PDF safe to use?
Yes. Everything happens in your browser. Your selected files are processed in your browser and are not uploaded to our server. Closing the tab clears the working session from this page; downloaded outputs remain on your device until you delete them.
Do I need to register or sign in?
No. No account, no email, no sign-up. Open the page and start using the tool immediately. Free to use, no signup needed.
Is there a watermark on the output?
No. PDF Tools Base never adds a watermark or branding to your output. Your final file is clean — just what you produced from the original.
Is there a file size limit?
There’s no fixed limit. Since processing uses your device’s memory, phones may struggle with PDFs over 50–100MB; desktops may handle larger PDFs but can still fail on very large or complex files. Large PDFs may be slow or fail depending on browser, device memory, page count, and PDF complexity — try smaller files, splitting first, or a desktop browser.
Does this work on mobile devices?
Yes. The tool works on all modern mobile browsers: Chrome on Android, Safari on iOS, Firefox, Edge, Brave. The drag-and-drop also accepts files from your phone’s file manager.
How many PDFs can I merge?
There’s no fixed limit. The merge pdf tool processes them in the order you drop them. For very large batches (50+), expect a few seconds of processing time on a typical laptop.
How does merging affect quality and PDF structure?
Pages are copied without rasterizing, so visual quality is normally preserved. The output PDF is rebuilt, so file structure, metadata, bookmarks, signatures, forms, or object byte order may change.