Practical guide
How to combine several PDFs into one document
A set of documents rarely arrives as one file. The contract comes without its appendices, the invoice without the proof of payment, the scanned pages one per file. Before you send them on, they need to become a single PDF, in the right order. This tool does that inside your browser: the files are never uploaded, and the merged document is written on your own device.
Merge PDF files in three steps
- Choose your .pdf files. Add them all at once or one at a time.
- Check the list under the drop zone — that is the order they will be combined in.
- Select Process locally and download velofile-merged.pdf. Your original files are left untouched.
The order is the order you add them
Nothing is sorted alphabetically and nothing is guessed from the file names. The first file you add becomes the first part of the document, and the list you see is exactly what you will get. If the order is wrong, the simplest fix is to clear the list and add the files again in the order you want.
If you only notice after merging that a page is out of place, move it with Reorder PDF pages rather than starting over.
Quality stays exactly as it was
The tool uses pdf-lib to copy each page as an object into a new document. Pages are not redrawn and nothing is recompressed: text remains selectable and searchable, vector logos stay sharp, fonts stay the originals, and images keep the resolution they had.
That is the difference from tools that turn pages into pictures to combine them, which leaves you with a file you can no longer search or copy text from. The merged file can still end up a little smaller or larger than the sum of its parts, because shared resources are written out again in one place.
What does not carry over
Bookmarks and the table of contents. Pages are copied, not the navigation structure around them. If one of your files had a clickable outline, the merged document will not.
Interactive form fields. Whatever was typed into a form stays visible on the page, but the fields stop being editable.
For a file you are sending to someone, neither usually matters. If your document depends on either, combine it with a desktop PDF editor instead.
The new file's own details
The merged PDF starts with fresh document properties: no title or author is copied across from the source files. It does record the software that produced it — VeloFile — and the date it was created, as every PDF writer does. If you want those gone before sharing it outside your organisation, run it through Remove metadata.
Password-protected files
An encrypted PDF cannot be read directly. Rather than skipping it silently, the tool stops and names the file it could not open. If you know the password, remove the protection with Unlock PDF first, then merge. If you do not have the password, there is no way around it, and that is intentional.
Before and after merging
Before: if you only need a few pages from a long document, take them out with Split PDF and merge just those.
After: a bundle made of several scans can get heavy. Compress PDF shrinks scanned pages — and if your document contains real, selectable text, it hands the file back unchanged instead of damaging it.
Limits
Up to 30 files per batch, 200 MB per file and 500 MB in total. Everything happens in the memory of this browser tab, so a very large batch on a modest computer or a phone can be slow. Closing other tabs helps.
Why it matters that this runs locally
The documents people merge are usually exactly the ones they would not leave on a stranger's server: contracts, identity papers, company records, letters from a lawyer. A typical online merge service uploads them, processes them remotely and keeps them for a period you do not control.
Here the files are read through the browser's File API and combined in memory. The network is used once, to fetch the PDF library itself; your documents are not part of that request, and closing the tab clears them.
Frequently asked questions
In what order are the files combined?
In the order you added them. The list under the drop zone shows that order exactly, and nothing is re-sorted by name. If it is wrong, clear the list and add the files again in the order you want.
Can I take only some pages from a file?
Not in this tool: merging takes every page of every document. Extract the pages you need with Split PDF first, then merge the results.
Why won't one of my files open?
Most likely it is password-protected. An encrypted PDF cannot be read directly, so it is refused with a message naming the file. If you have the password, unlock it first and come back.
Are bookmarks and form fields kept?
No. The pages and everything drawn on them are copied, but document-level structures — the bookmark outline and interactive form fields — do not carry over. Filled-in values stay visible; the fields simply stop being editable.
Does merging reduce quality?
No. Pages are copied as they are, not redrawn or recompressed. Text stays selectable and searchable, and images keep the resolution stored in the original.
How many files can I merge at once?
Up to 30 files in one batch, at most 200 MB per file and 500 MB in total.
Are my documents uploaded anywhere?
No. The files are read from your device, combined in this browser tab's memory and handed back as a download. There is no account and no server that receives them.