Merge PDF combines multiple PDF files into one, in the order you add them, without flattening, re-rendering, or altering a single page in the process. It's the direct fix for the everyday problem of having several related PDFs — scanned forms, chapters, statements — that really belong together as one document, but were created or received separately.
How to use Merge PDF
- Choose your privacy mode before adding any files. Sensitive mode processes the merge entirely in your browser tab; Normal mode uploads the files to our sandboxed server, useful if you're on a device with limited memory or need to merge larger files than Sensitive mode's on-device limit allows.
- Add your PDFs — Sensitive mode and Normal mode both support multi-file merges, with Normal mode allowing up to 5 files per job and Sensitive mode's limit depending on your device's available memory (shown before you start).
- Add your files in the order you want them to appear in the final document — the sequence you add them in is the order pages come out in, so add them in that order from the start (there's no reordering after adding yet; remove and re-add a file if you need to fix its position).
- Click Process to combine them into a single PDF. The tool concatenates the page trees from each source file, so every page keeps its own content, fonts, and embedded resources exactly as they were.
- Download the merged file. Every page from every input file is preserved exactly, in the sequence you chose, with nothing dropped or re-encoded.
Worked example
Combining a cover letter with a resume and reference letters
A common case: you have a cover letter (1 page), a resume (2 pages), and two reference letters (1 page each) as four separate PDFs, and a job application wants a single document. Add the cover letter first, the resume second, and the reference letters last, in that order — the merged output is a single 5-page PDF matching exactly the sequence you added them in. Page numbering, orientation, and content on every page stay untouched; merging only changes how many files you have, not what any of them contain. If the resume happens to be in landscape orientation while everything else is portrait, that's preserved too — a merged PDF can freely mix page orientations and sizes, because merging works at the page level, not by forcing every source document into a shared layout.
Processing limits & specifications
| Mode | Location | Max file size | Retention |
|---|---|---|---|
| Sensitive mode | Your device (WASM) | Up to 75 MB (typical device) | Never stored / zero egress |
| Normal mode | Server sandbox | 300 MB | Deleted when you close the page |
Frequently asked questions
How many files can I merge at once?
In Sensitive mode, the limit depends on your device's memory and page-count budget (shown on this page). In Normal mode, up to 5 files per job.
Can I control the order of the merged pages?
Yes — the order you add the files in is the order they appear in the output. There's no automatic reordering by filename or date, and no way to reorder after adding yet, so add them in your intended order (or remove and re-add one if you need to fix its position).
Does merging affect page size or orientation?
No. Each page keeps its own original dimensions and orientation. A merged PDF can freely mix portrait and landscape pages, or different page sizes, exactly as the source files had them.
What if one of my files is password-protected?
Encrypted PDFs are detected and rejected with a clear error rather than merged incorrectly. Remove the password from that file first, then merge.
Can I merge more than PDFs — like a Word document and a PDF?
Not currently — Merge PDF accepts PDF files only. Convert other formats to PDF first with their originating application.
Will merging affect fonts or embedded images in any of the source files?
No. Each source PDF's fonts, images, and other embedded resources come across in the merged file exactly as they were. Merging doesn't re-render or recompress anything — it's a structural combination of existing pages.
Can I remove a file from the list after adding it, before merging?
Yes — you can remove any added file before clicking Process, without needing to start over and re-select every other file.
Does the output filename tell me anything about what was merged?
The downloaded file is named after your first input file with a "-merged" suffix, so you can distinguish it from the originals; it doesn't encode a full history of every source file that went into it.
Is there a difference in the result between merging in Sensitive mode versus Normal mode?
No — the same underlying qpdf-based merge logic runs in both modes (a WebAssembly build in your browser for Sensitive mode, the equivalent engine on our server for Normal mode), so the merged output is structurally the same either way. The choice between modes is about where the processing happens, not what the result looks like.
Can I merge PDFs of very different lengths, like a 1-page cover with a 300-page report?
Yes — there's no requirement that merged files be similar in length or content type. The output simply concatenates every page from every input, in your chosen order, regardless of how the page counts compare between files.