How to combine PDF files
- Drag two or more PDFs onto the tool above, or click it to choose them. Anything that isn’t a PDF is skipped with a short note.
- Check the list. Each file shows its page count and size, so a wrong file stands out.
- Use the up and down arrows to set the order, and the ✕ button to remove anything you don’t need.
- Click Merge PDFs (the button shows how many files are included), then download
merged.pdf.
The list order becomes the page order: every page of the first file, then every page of the second, and so on. Your original files are not modified; you download a new document.
Why merge contracts, tax forms and medical records locally
The documents people most often need to combine are also the ones they least want to hand to someone else’s server: a signed contract and its exhibits, a year of bank statements for a tax preparer, lab results and referral letters for a new doctor, or an offer letter, ID scan and onboarding forms for HR. A typical online combiner uploads each file and processes it on a remote server, so you have to trust whatever happens to it there.
pd00 works differently. The merging code runs inside your browser tab, and your PDFs are read from your own disk straight into that tab’s memory. The page’s Content-Security-Policy only allows network connections back to pd00.com and to Cloudflare’s anonymous page-view counter, which never receives documents; the browser blocks every other destination. You can check this yourself in the DevTools Network panel; the steps are on our privacy page. Once the page and its PDF engine have loaded (that happens when you add your first file), you can even disconnect from the internet and keep merging.
Getting the page order right before you merge
Files usually arrive in the order your file picker lists them, which is often alphabetical. The quickest way to control the order is to rename the files before adding them: 01-cover-letter.pdf, 02-contract.pdf, 03-exhibit-a.pdf. Keep the leading zeros; without them, some apps sort “10” ahead of “2”.
If renaming isn’t practical, add the files in any order and fix it in the list. Each arrow moves a file one position. Changing the order or removing a file after a merge clears the previous result, so the file you download always matches the list on screen.
The tool orders whole files, not individual pages. To use only some pages of a document, or reverse them, run it through Split PDF first, then merge the pieces.
What merged.pdf keeps and what it leaves behind
Pages are copied into the new document as they are. Nothing is turned into an image or re-compressed, so text stays selectable and searchable, vector drawings stay crisp at any zoom, and scanned pages keep their original resolution. The size of merged.pdf is roughly the total of the files you put in, so merging is not a way to make anything smaller.
| Part of the source PDFs | In merged.pdf |
|---|---|
| Page content: text, fonts, images, drawings | Copied unchanged, no quality loss |
| Selectable, searchable text | Kept |
| Bookmarks (the outline panel) | Not carried over |
| Fillable form fields | May stop working after the merge |
| Document title and author properties | Not copied; the merged file starts fresh |
| Password protection | Locked files can’t be added; unlock them first |
If a filled-in form must stay usable, send it as a separate attachment instead of merging it.
Combining photos and scans with your PDFs
The merge tool accepts PDFs only. If you drop a JPG or an iPhone photo in with your documents, it is skipped and a note points you to the image converter. To mix them, first turn the images into a PDF with JPG to PDF, which also takes PNG, WebP, AVIF and HEIC, or use HEIC to PDF for a batch of iPhone photos. Then add that PDF to the merge list alongside your other files and move it into position.
A common case: a receipt photo that belongs behind a typed expense report. Convert the photo, put the report first and the receipt second, and merge. If high-resolution scans make the result too big to email, run it through Compress PDF afterwards.
Large merges, locked files and other limits
- Memory. There’s no fixed limit on the number of files, but everything is held in your browser’s memory while the merge runs. A computer handles large jobs comfortably; a phone or older tablet may slow down or reload the tab once the files add up to hundreds of megabytes. If that happens, close other tabs or switch to a computer.
- Password-protected PDFs. Encrypted files can’t be opened, so they can’t be merged. Remove the password in the app you normally use to open the file, save a copy, and add that copy.
- No editing. This tool doesn’t change text, add signatures, rotate pages, run OCR on scans or convert to Word. It joins documents and nothing more.
- Browsers. It runs in recent Chrome, Edge and Firefox, and in Safari 16.4 or later on Mac, iPhone and iPad.