Step 1 · Choose the PDFs
Drag your PDFs here or look for them on your computer
PDF up to 25 MB each · maximum 10 documents and 75 MB in total
How to join multiple PDFs into one
- Add the documents with the selector or by dragging them to the upload area.
- Check the order and use the arrows to move each document up or down.
- Press “Join PDF” and wait for local processing to finish.
- Download the result and check that the pages appear in the expected order.
Joining is not compressing
This tool copies the pages of each document into a new PDF. Does not compress again images or remove fonts, forms or internal data to reduce weight. That's why he final file can weigh practically the same as the sum of the originals, or even somewhat more for the added structure. If you need to reduce the size, you will have to use a compressor specific; no reduction is promised here.
What is conserved and what can change
The pages and their visible content are preserved, including images and most of the annotations that are part of the page. However, PDFs are complex formats: bookmarks, interactive forms, layers, attachments, digital signatures and some actions They may not be preserved or may stop working when you rebuild the document. Always check the result before using it in an important procedure.
Privacy, memory and limits
Files are read with the API File from the browser and are processed with pdf-lib in
memory. There are no upload requests, accounts or external services. The limit is
25 MB per PDF, 75 MB total, 10 documents and
300 pages combined. On mobile phones with little memory it is advisable to join few documents
big at the same time.
Protected or damaged PDFs
If a document is password protected, the tool detects it and displays an error Of course: he doesn't try to decipher it. It also does not repair corrupt files. Remove the protection with the original app or re-download the PDF before merging it.
Browser Compatibility
Works on current versions of Chrome, Edge, Firefox and Safari with JavaScript modules,
File, Blob and canvas. Processing uses pdf-lib and PDF.js served
from this same site; no libraries are loaded from CDN. A very old browser without
module support will not be able to run the tool.
Frequently asked questions
Are PDFs uploaded to FasTools or a third party?
No. The join is done in your browser. The site only delivers the HTML, CSS and libraries; The content of your documents does not travel to the server.
Can I change the order after adding them?
Yes. Each document has buttons to upload or download it. You can also remove it and return to add it in the position you want.
Does the resulting PDF weigh less?
Not necessarily. Joining does not compress: it can weigh the same or more. The page shows the size real input and output so you can check before downloading.
Are forms and bookmarks preserved?
It is not guaranteed. pdf-lib copies the pages, but the interactive forms, bookmarks, signatures and attachments can be lost. For complex documents, review the final file.
Can I join a password protected PDF?
No. The tool does not decrypt documents. You must remove the password first from the application you created it with.