UFOZoo

Merge PDF Free — Combine PDFs into One File Online

Merge multiple PDFs into one file free. Combine scans and e-book chapters with drag-and-drop reordering. No uploads: everything runs in your browser.

Features

  • ✓Merge unlimited PDF files into one document in seconds, entirely in your browser
  • ✓Combine scanned documents, contracts, e-book chapters, and reports into a single organized PDF
  • ✓Drag-and-drop file opening: add dozens of PDFs at once without individual uploads
  • ✓Instant page count for every file, displayed in the list before you merge
  • ✓Reorder files with up and down buttons: the file at the top of the list becomes page 1
  • ✓Every page keeps its original layout: fonts, images, vector graphics, and links are preserved
  • ✓Batch merge: process all opened PDFs in one click with a live progress counter
  • ✓Add more PDFs to an open merge session at any time without starting over
  • ✓Remove unwanted files before merging with a single click
  • ✓Save the result as one standard PDF ready for printing, sharing, or archiving
  • ✓100% free with no sign-up, no watermarks, and no file count or size limits
  • ✓Fully client-side processing: files never leave your device, safe for confidential documents

How to Use

  1. 1Click the open area or drag and drop one or more PDF files onto the tool
  2. 2Open multiple PDFs at once: the page count of each file appears as soon as it is read
  3. 3Check the page count and file size shown next to each filename before merging
  4. 4Use the up and down buttons to arrange files: the file at the top becomes page 1
  5. 5Click the remove button to drop any file you do not want in the merged document
  6. 6Click Merge PDFs to combine all files into a single document
  7. 7Watch the progress counter while merging: it shows the file currently being processed
  8. 8Click Save PDF to save the merged document to your device
  9. 9How to merge scanned PDFs: open all scan files, sort them by page order, then merge them into one document
  10. 10How to merge e-book chapters: open each chapter in reading order and merge them into a single book file

Frequently Asked Questions

How many PDF files can I merge at once?

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There is no fixed limit on the number of files. You can merge as many PDFs as your device's memory can hold. For the smoothest experience, we recommend keeping a single merge session under 100 files.

Is there a limit on the total file size?

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There is no imposed size limit. The only constraint is the memory available in your browser tab. Very large PDFs (hundreds of MB) take longer to process, so it is best to merge them a few files at a time.

Will the merged PDF lose quality?

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No. Pages are copied into the new document exactly as they are: text, fonts, images, and vector graphics are preserved without recompression, so the merged file keeps the full quality of the originals.

Can I change the order of pages before merging?

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Yes. Use the up and down buttons next to each file to reorder them. The file at the top of the list becomes page 1, the second file becomes page 2, and so on.

Can I merge scanned PDFs?

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Yes. Scanned PDFs are image-based documents and merge just like any other PDF. Open all your scan files, sort them by page number, and merge: ideal for combining multi-page scans into one document.

Can I merge PDFs that have different page sizes?

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Yes. Every page keeps its own original size in the merged document, so PDFs with mixed A4, Letter, and custom page sizes combine without any scaling or distortion.

What happens if a file is corrupted or password-protected?

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The file is marked as unreadable in the list and skipped during merging. Remove it and try again. Password-encrypted PDFs are not supported: open them in a PDF reader first and save a copy without a password.

Is my data safe?

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Completely. All merging happens locally in your browser with JavaScript. Your files are never uploaded to any server, which makes the tool safe for contracts, medical documents, and other confidential PDFs.

Does the tool work offline?

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Yes. Once the tool page has loaded, merging works fully offline because no server is involved. You can use it on a plane, on a train, or anywhere without an internet connection.

Can I merge the same PDF twice?

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Yes. You can add the same file more than once and each copy contributes its pages to the result: useful when you want to duplicate a section or create a repeating template.

Does it work on mobile devices?

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Yes, the tool is fully responsive. On a phone or tablet, open PDFs from the Files app or downloads folder and merge them with the same touch-friendly controls.

Is the tool really free?

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Yes. Merging is completely free with no sign-up, no watermarks, and no page or file limits. The tool runs entirely in your browser, so there are no server costs to cover.

Does the merged PDF have a watermark?

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No. The merged document is a clean, standard PDF with no watermarks, no added branding, and no footer stamps. The output matches your original files in quality, just combined into one document.

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