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Merge PDF Files

Drop PDFs, put them in order, download one file. Nothing leaves your browser.

Merging PDFs does not mean re-rendering them. This tool uses pdf-libto copy each page object-by-object from its source document into a fresh one: the page’s content stream, its fonts, its embedded images, and its vector drawing commands are transplanted intact, along with every indirect object they reference. Nothing is rasterized, so text stays selectable, vectors stay sharp at any zoom level, and there is no quality loss — the merged file is structurally new but visually identical, page for page. The whole process runs in your browser; your documents are never uploaded anywhere.

Drop PDF files here, or

Up to 20 files, 64 MB each. Stays in your browser — nothing is uploaded.

How to use

  1. Drop your PDF files

    Drag two or more PDFs onto the dropzone, or click to choose them. Each file is opened locally and its page count is shown — encrypted or damaged files are rejected with a message rather than silently producing a broken merge.

  2. Put them in order

    Use the up/down arrows to arrange the files. The merged document contains every page of the first file, then every page of the second, and so on — exactly the order shown in the list.

  3. Merge

    Click the Merge button. Pages are copied losslessly from each source into a single new PDF, entirely in your browser. Large files simply take a moment longer; nothing is sent to a server.

  4. Download

    Click Download to save the combined file as merged.pdf. If you then reorder, add, or remove files, the old result is discarded and you merge again — the tool never hands you a stale file.

Frequently asked questions

Are my PDFs uploaded to a server?
No. The files are read into memory in your browser tab, merged there with the pdf-lib JavaScript library, and the result is offered as a local download. There is no upload request at all — you can watch the network tab to confirm.
Is there any quality loss when merging?
No. Pages are copied at the object level, not re-rendered: text, fonts, vector graphics, and embedded images move into the new file byte-for-byte. Nothing is converted to a bitmap, so the merged pages are visually identical to the originals at any zoom level.
Can I merge password-protected (encrypted) PDFs?
Not directly. If a file is encrypted, the tool rejects it with an error when you add it rather than producing a corrupt merge. Remove the password first — most PDF viewers can save a decrypted copy once you have opened the file with its password — then add the decrypted file here.
What are the file and page limits?
Up to 20 PDFs per merge, each up to 64 MB. There is no hard page limit — the practical ceiling is your device’s memory, since every source file and the merged result live in RAM while the tool works. Hundreds of pages merge comfortably on an ordinary laptop.
Does the page order follow the list order?
Yes, exactly. The merged PDF contains all pages of the first file in the list, followed by all pages of the second, and so on. Use the arrow buttons to reorder files before merging; any change to the list invalidates the previous result so you always download what you see.
Are bookmarks and form fields preserved?
Page content, yes — everything drawn on the pages survives intact. Document-level structures are a different story: bookmarks (the outline tree) and interactive form field definitions live outside the pages, and because this tool copies pages into a brand-new document, those structures may be lost or stop working in the merged file. If your PDFs rely on fillable forms or a navigation outline, check the result before discarding the originals.

About

How PDF page copying actually works

A PDF is a graph of numbered indirect objects: a page object points to a content stream (the drawing commands) and a resource dictionary, which in turn points to font programs, image XObjects, color spaces, and graphics state dictionaries — each of those an indirect object of its own, possibly shared between pages. Copying a page therefore means walking that graph: pdf-lib traverses every object the page references, deep-copies each one into the destination document, assigns it a new object number, and rewrites all the cross-references so the transplanted graph is self-consistent. The destination file then gets its own cross-reference table and trailer. That is why the output is a valid, standalone PDF rather than a fragile concatenation of two files.

Why lossless copying beats rasterizing mergers

Some merge tools take a shortcut: they render every source page to an image and build a new PDF out of those images. The result looks similar at one zoom level but is strictly worse — text is no longer selectable or searchable, vector line art becomes pixels that blur when you zoom or print, file sizes balloon because compressed fonts and vectors turn into bitmaps, and screen readers lose the text entirely. Object-level copying avoids all of that: the merged file keeps real text runs, real font programs, and real vector paths, so it prints at full resolution, stays accessible, and is usually about the size of its inputs combined.

Sources & references

Authoritative references behind the math, constants, and tables on this page. Verified by Buğra Sözeri on the dates shown and re-checked at every deploy.