Merge PDF

Merging PDF files is one of the most common document tasks in any office or study routine. Whether you are combining several scanned receipts into a single expense report, stitching together chapters of a thesis, or assembling a contract from separate signed pages, having one clean PDF is far easier to send, print and archive than a folder full of loose files.

ColaPDF merges your documents directly in the browser. Because nothing is uploaded, even confidential files — legal agreements, payslips, medical records — stay completely private on your own device. You can add as many PDFs as you want, drag the page thumbnails to get the exact order you need, rotate individual pages that came in sideways, and export a single combined document in seconds.

How it works

1. Upload two or more PDF files using the drop zone or click to browse
2. Drag files to reorder them if needed — the order you see is the order they merge
3. Click "Merge PDF" to combine all files into one
4. Download your merged PDF instantly — no email, no wait

Tips

• Drag pages within the preview to fine-tune the final order before merging — the order you see is exactly the order you get.
• Mixing portrait and landscape pages is fine; each page keeps its own orientation in the merged file.
• If a PDF is password-protected, unlock it first with the Unlock PDF tool, then merge.
• For very large documents, merge in smaller batches if your device runs low on memory.

Frequently asked questions

How many PDFs can I merge at once?

As many as you like. There is no hard limit — the practical limit depends on your device memory.

Are my files uploaded to a server?

No. All merging happens locally in your browser. Your files never leave your device.

Will merging reduce PDF quality?

No. The merge is lossless — images, fonts and formatting are preserved exactly as in the originals.

Can I merge password-protected PDFs?

You need to unlock them first using the Unlock PDF tool, then merge.

Is it free?

Yes, completely free with no sign-up required.