📎 Merge PDF
Combine PDFs into one file without uploading them anywhere. Set the order, see page counts, flatten form fields. Runs entirely in your browser.
Choose PDFs, or drop them here
Merged in this tab. Your documents are never uploaded to a server.
Bookmarks, tags and attachments belonging to the source files are not carried across; pages, text, images and links are. Password-protected files have to be unlocked in a PDF reader first.
What Merge PDF Does
Merging PDFs is a structural operation, not a rendering one. A PDF is a set of objects — pages, fonts, images, the vector instructions that draw the text — indexed by a cross-reference table. Combining two documents means copying one file’s page objects and everything they depend on into the other, then rebuilding the index. Nothing is rasterised, nothing is re-compressed, and the text stays exactly as selectable as it was.
That is why a merged file is roughly the sum of its parts and why quality is not a question here: there is no quality setting because no pixel is touched.
The part that is a question is privacy. Every dominant tool on this search — iLovePDF, Smallpdf, Adobe, PDF24, Sejda, PDF2Go — uploads your document to a server, processes it there and promises to delete it afterwards. People merge contracts, payslips, medical letters, tax returns and bank statements. This tool reads the files with JavaScript in your own tab; the site is a static export with no backend, so there is nowhere for a document to be sent. Load the page, disconnect from the network, and it still works.
The one thing worth thinking about before merging is form fields, because that is where merging quietly produces a wrong document rather than an error.
How to Use Merge PDF
- Add two or more PDFs, or drop them onto the box
- Put them in the order you want with the arrows, or sort by file name
- Tick "flatten form fields" if any of them are filled forms
- Name the output and merge — the combined file saves straight to your device
What survives a merge and what does not
Page content comes across intact. Document-level structure mostly does not.
| Element | Carried across? | Note |
|---|---|---|
| Page content — text, images, vectors | Yes | Copied as objects; nothing is re-rendered |
| Fonts | Yes | Embedded fonts come with the pages that use them |
| Internal and external links | Yes | Links to pages that came along keep working |
| Form fields | Yes | But duplicate field names across documents collide — see below |
| Bookmarks / outline | No | The source documents’ outline trees are not rebuilt |
| Attachments and document JavaScript | No | Dropped with the rest of the document catalogue |
| Tags and accessibility structure | No | Re-tag in a full editor if the output must stay accessible |
Where the file is processed
The practical difference between this and the tools that outrank it.
| Tool | Where the PDF goes |
|---|---|
| This page | Nowhere. Read and written in your browser tab |
| iLovePDF, Smallpdf, PDF24, Sejda, PDF2Go, Adobe | Uploaded to the provider’s servers, processed, then deleted on their schedule |
How to Read Your Result
Flatten forms when merging filled documents
Two PDFs generated from the same template both name a field "Name". Merged live, those become one field with one value, so the second copy shows the first copy’s answers. Flattening converts the current values into ordinary page content, which fixes it permanently. Leave flattening off only if the merged document still has to be filled in.
The merged file will not be smaller
Merging is concatenation of objects, not compression. Two 5 MB files make roughly a 10 MB file. Shared fonts may save a little; nothing else does.
Order is set before you merge, not after
Reordering pages afterwards means a second operation. Use the arrows or sort by name first — natural sorting puts scan-2 before scan-10, which plain alphabetical sorting does not.
Limitations & Accuracy Notes
- Password-protected and encrypted PDFs are refused rather than mangled. Unlock a copy in a PDF reader first.
- Bookmarks, attachments, document JavaScript and accessibility tags from the source files are not preserved.
- Digital signatures are invalidated — that is inherent to changing the document, not specific to this tool.
- Everything is held in your device’s memory while it is combined, so very large documents can exhaust an older phone.
- Pages are not resized to a common paper size; a merged A4 and Letter document keeps both page sizes, which is usually what you want.
Frequently Asked Questions
Are my documents uploaded to a server?
Is there a limit on the number or size of files?
Does merging reduce quality or re-compress anything?
What is lost when PDFs are merged?
Why would I flatten form fields?
Can I merge a password-protected PDF?
References & Further Reading
- ISO 32000-1 / PDF 32000 specification (Adobe copy) — The document structure — page tree, catalogue, cross-reference table — this operation manipulates
- pdf-lib — The open-source library doing the page copying, running in your browser